The last couple of weeks could serve as a case study for anyone looking into where political correctness, free speech and the priorities of TV networks intersect. It all began with Kathy Griffin posing with a severed head that resembled Donald Trump. The shock comic was berated for the stunt, had several bookings cancelled and was promptly fired from her New Year’s Eve gig at CNN. Then Bill Maher referred to himself as a “house nigger” in some off-the-cuff “banter” on his HBO show. The cable giant called it “inexcusable”, but he kept his job after apologising twice, and partaking in a carefully controlled comeback show on which black guests lined up to tell him how much of an idiot he had been. The CNN host, scholar and writer Reza Aslan was then fired for calling Donald Trump a “piece of shit” on Twitter, while pointing out that the president was opportunistically using the London terror attacks as a way to support his own proposed Muslim ban.

The apologies all followed a similar pattern: contrite-ish and cringeworthy. Griffin’s mea culpa was all about crossing the line of good taste, a habit on which her career is based. “I went way too far. The image is too disturbing. I understand how it offends people. It wasn’t funny. I get it. I’ve made a lot mistakes in my career, I will continue. I ask your forgiveness,” she said. Maher put it down to being caught up in the moment. “I regret the word I used in the banter of a live moment. The word was offensive, and I regret saying it and am very sorry,” he wrote. Aslan’s was all about linguistic miscalculation. “I should have used better language to express my shock and frustration at the president’s lack of decorum and sympathy for the victims of London. I apologize for my choice of words,” he said.

Bill Maher and Eric Michael Dyson

Three instances of offense, three apologies, but only one person kept his job. To really understand what happened, you need to know what’s at stake for the networks. HBO and Maher have a long relationship. He’s not only part of the cable giant’s most recognisable “talent”, but his production company is part of the team that brought Vice’s documentaries and news to the channel. During his Sunday night discussion/rehabilitation with Michael Eric Dyson, he said: “It’s not like I’ve made a career out of this.” That’s true. His career isn’t based on saying the n-word, but it is based on being offensive toward certain groups. He’s said far worse about Muslims, something that Aslan has consistently pointed out. Why would saying “nigger” be the hill that he died on?

Griffin was an annual guest on CNN, booked to play the gaudy ying to Anderson Cooper’s straight-laced yang on its New Year’s Eve programme. Nothing was at stake for CNN, really – all the channel had to do was replace her with another comedian. She’s since talked about how the Trump administration is trying to ruin her career, but being pitched as the anti-Trump comic isn’t a bad place to be in 2017. Aslan was probably a harder decision for CNN, as he has been – along with W Kamau Bell, Lisa Ling and Anthony Bourdain – part of the network’s shift to include more diverse and challenging programming on weekend evenings.

For CNN, the issue seems to be credibility and optics rather than genuine offense over Aslan’s choice of words. It’s been on the frontline of Trump’s war with the media. Its journalists have been called out personally by the president at press briefings, punished for their peddling of – in his mind at least – fake news. After having to backtrack on stories, management probably decided it wasn’t in the channel’s best interests to stand behind talent that referred to the president as excrement. But should they?

Kathy Griffin gestures during a news conference to discuss the fallout from her ‘severed head’ photoshoot. Photograph: Mark Ralston/Getty Images

For Griffin and Maher, these faux pas were hyper-extensions of their instincts to offend. Despite what Maher may claim, they’ve both made a living out of this kind of outrage humor. But for Aslan, a different set of rules apply. He’s not really a journalist; he’s definitely not a comic; he’s a scholar who’s transferring into the role of host – and he learned pretty quickly that that doesn’t give him much cover when it comes to being offensive. “Obviously I am very disappointed in this decision,” wrote Aslan in his statement about the cancellation of his show Believer on CNN. “Believer means a great deal to me and to the countless viewers it’s reached. Its message of religious tolerance and exploration is extremely important right now.”

He’s right. It’s the kind of show that is needed. The issue comes at a time when it appears as if abusive language of a racial nature is not deemed as offensive or unpalatable – instead, it is seen as something that’s considered distasteful to a certain audience. The downfall of Milo Yiannopoulos – a guest of Maher’s – didn’t come because he made racist remarks about Leslie Jones, but because he seemed to endorse paedophilia. Casually using the n-word or veering into Islamophobia is easy to recover from: just apologise and look contrite or don’t bother saying sorry at all.

In the age of Trump, the bar of what’s considered sayable in public life has been lowered to new depths – but that doesn’t mean that anything goes for those who criticise the president. Far from it: those who are challenging his divisive rhetoric on the grounds of misogyny (Griffin) or religious intolerance (Aslan) will be judged harshly if they’re seen to overstep the mark. (Just look at the fallout from the Shakespeare in the Park’s production of Julius Caesar.) But those voices of dissent are needed. Whether Griffin should have taken a photo with a “severed leg as well”, as Jim Carrey suggested, is open for debate. But should she be able to continue to mock Trump? Absolutely. Aslan’s role as one of the most prominent Muslim voices in American media is necessary, and hopefully another network will give him the chance. He should probably start by calling up HBO.