There haven’t been many laughs in Manuel Oliver’s life since his 17-year-old son Joaquin was shot and killed at his Florida high school last Valentine’s Day. A grief-filled year since his “best friend” died has been punctuated by Oliver highlighting the tragedy of gun violence in America through an emotional, raw and gritty form of art activism.

So when the disgraced comedian Louis CK fuelled his comeback attempts with some insensitive jokes about the Parkland survivors, it was a given that Oliver would speak up for his son and the 16 other victims in the best way he knows how.

“Hear the one about a kid who walks into the school on Valentine’s Day?” Oliver asks in a derisive stand-up comedy club style routine produced as a video clip for Change the Ref, the gun safety advocacy organisation the family set up in the wake of their son’s killing.

“Skinny kid, wearing headphones, gets dropped by his dad. Says I love you and walks into the school. And then gets shot to death a couple of hours later,” Oliver says, the non-punchline emphasised by a crashing cymbal.

Manuel Oliver, whose 17-year-old son was shot dead in Parkland, in a video created by gun safety advocacy group Change the Ref, entitled Stand Up Against Gun Violence

It was a pointed response to a comedian who misused his first amendment right in order to bully the teenage survivors of the shooting, according to Oliver, who will attend Tuesday’s evening’s State of the Union address as a guest of Florida Democratic congressman Ted Deutch.

“I had an argument with someone [else] when I was in New York, in the middle of the village where all the comedy nightclubs are,” Oliver told the Guardian in an interview last week, before the video produced by Change the Ref went viral. “We had an issue with this comedian who made jokes about the Parkland kids, this guy said ‘well, we have the right according to the first amendment of freedom of speech’.

“I said that’s what you’ve got wrong. We have amazing rights but nobody wrote those rights so you can bully people. You shouldn’t be talking shit about anybody, that right was made for you to defend yourself.”

Speaking up for those who no longer can has become the hallmark of Oliver’s campaigning over the last year, which has seen him and his wife Patricia, Joaquin’s mother, travelling across United States and overseas, often in the company of the March for Our Lives student movement and promoting the gun control message of Change the Ref.

Oliver, who was raised by a creative family including photographers, artists and a civil engineer father in his native Venezuela before moving to the US 16 years ago, has produced a series of sardonic giant wall murals, attention grabbing art installations and even a lifesize three-dimensional printed sculpture of his son. The “3D activist” was prominent at a die-in at the US capitol building in Washington DC last month, while Oliver’s self-styled “Artivism” has been displayed in many other cities that have experienced mass shootings, including Las Vegas and Orlando, and in Dallas at the National Rifle Association summit last May.

“None of us were born to hide our face, wash our hands or turn the page and try to be happy and comfortable again. I don’t even know if that’s possible,” Oliver said of himself, his wife and Joaquin’s sister Andrea.

“We decided that what we know, what we learned, we’re going to use it. I’m doing this because it’s my best tool to fix what I think is wrong. This is a problem beyond Parkland. By travelling around the nation, around the world, by knowing people that suffered the same situation we suffered on February 14th, that tells me that we have a common issue.

Students sign a poster with photos of Joaquin Oliver, one of those killed in the shooting at Marjory Stoneman Douglas high school on 14 February 2018. Photograph: Giorgio Viera/EPA

“The good news, if there is such a thing, is that I have a spotlight on my speech, my thoughts and activism. Most people don’t. Today 100 people will die in America because of gun violence. They won’t have the chance to talk to someone like you – nobody knows them. They have no voice.”

Though friends with the other bereaved families of the 14 students and three adults killed at Marjory Stoneman Douglas high school, Oliver, one of the most outspoken members of a group entwined by tragedy, insists he speaks for only himself and his son.

Some families have channelled their activism efforts locally, seeking the removal of Broward county’s sheriff and superintendent of schools whom they blame for allowing a 19-year-old former student to return to the campus with an assault rifle (Oliver supports the officials’ removal but does not see a need to celebrate it).

Others have worked with Florida’s Republican politicians and Donald Trump’s administration to pursue legislation intended to harden security in schools, including the controversial proposal to arm teachers.

“I had an invitation to the White House and I said no. There is no reason for me to go,” Oliver said. “Some families were there, there’s that beautiful picture in the Oval Office, Donald Trump sitting in the centre, in a very powerful attitude and the parents of the victims from Parkland standing beside him and showing respect.

“Fuck that. I don’t play that role, and I don’t play that role because it will be a contradiction to all the things that happened. It’s not about Donald Trump, forget him. But whoever is in the White House, is he part of the solution or not?

“This administration in particular is very attached to the gun lobby, many of the politicians have received donations from the gun lobby and the NRA. So it’s obvious they cannot be part of the solution. Their solution is arming and arming more people. Australia never thought that would be part of the solution, the United Kingdom never thought that, Japan, Canada, never thought that.

“Only in America can a 19-year-old go to a store, buy an AR-15, buy ammunitions, go home, load it, go to school the next day and murder people. Or go to a church, a bank, a yoga salon … and start shooting people like crazy.”

Oliver prefers for his message to be carried in a more personal way, one that reaches politicians, and other people, as individuals. He met Nancy Pelosi in Washington last year, before the Democratic party leader became the House speaker.

“I asked her, ‘Can I call you Nancy? It’s not that I want to be informal, but I want to get close to you in our conversation. Do you have kids, Nancy? Do you have grandkids, Nancy?’ ‘Yes I do’. ‘Are they safe now?’ ‘Yes’. But you don’t know. The same way I didn’t know.

“I said I don’t know if you’re going to be able to solve this, because to my mind it’s a cultural thing. But I’m going to ask you to keep in mind when you have power that there’s a lot of people losing their lives because the politicians aren’t passing the laws they need to be passing.”

Oliver says he continues to talk to the politicians he encounters. “You are there because we voted for you, because you made promises to us,” he said.

“We’re not going to be home waiting for you, we’re going to be here reminding you, just in case you forget about it. Yesterday 100 people lost their lives. What did you do yesterday? Today 100 people will die. What are you going to do today to help them? Tomorrow, another 100 people will die. What are you planning to do to stop this?

“But still you have these politicians that will never change their mind, not to mention they’re paid for. I paid the biggest price you can pay to be where I am. There’s no way anybody can return me the value of my son, so I’m here forever.”

