The philosopher and activist Cornel West has labelled the US president, Donald Trump, a “gangster” whose vision of America is “triumphing” during a fiery episode of the ABC’s Q&A program in which panellists also traded blows on energy and free speech.

The Coalition senator Eric Abetz refused to back his government’s own energy policy during the program, saying it was “premature” to say whether he supported the policy.

The conservative Tasmania senator offered a lukewarm assessment of the national energy guarantee, saying Australia’s attempts to reduce emissions would not make “one scintilla of difference” to climate change.

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On the same night that the government’s backbench committee formally offered its support for the Neg to be debated in the Coalition party room, Abetz repeated his previous calls for a federal takeover of the AGL-owned Liddell power station.

And while he stopped short of repeating Tony Abbott’s threat to cross the floor to vote against it, Abetz stopped refused to back the Neg, describing it simply “a framework”.

“Until such time as we have all the detail, I think it’s premature to say you fully support it or fully oppose it,” he said on Monday night. “But it seems to me that the driver behind the Neg is the Paris agreement, and India’s not bound by it, China isn’t nor is the US.

“Irrespective of your views [on] climate change … the simple fact is us doing our alleged bit in relation to Paris will not make one scintilla of difference to the world environment but it will make a huge difference to our economic wellbeing, to jobs and to standard of living in Australia.”

In an episode that lurched from energy policy to the soul of the United States and the limits or otherwise of free speech, Abetz found himself seated next to the philosopher and activist Cornel West.

As well-known for his criticism of Barack Obama and the writer Ta-Nehisi Coates as for his civil rights activism, West, a Harvard professor visiting Australia as part of a debating tour, warned the US was experiencing a “spiritual blackout” and an “escalation of corruption and criminality” following Donald Trump’s election as president.

West labelled Trump a “gangster” and said his version of America was “triumphing” while the one envisioned by Martin Luther King was “wrestling with defeat”.

Warning that the US was in a state of “deep decay”, he pointed to the increasing division between rich and poor, and rates of child poverty, as signs the country is in “imperial meltdown”.

Challenged by Abetz – who pointed to falling unemployment in the US and said “your black brothers are getting jobs” – West said he was talking about “moral and spiritual issues, not just the numbers”.

“Hitler and Mussolini had low unemployment rate [and] they made the trains run on time,” he said.

Monday’s panel also included Canadian graduate student and teaching assistant Lindsay Shepherd, who became a lightning rod for debates over free speech and academic freedom when she was reprimanded by her university for showing a talk by academic Jordan Peterson to one of her classes.

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Peterson is in part controversial for his refusal to agree to use gender-neutral pronouns to describe transgender people, and on Monday Shepherd said she considered herself a progressive but wanted “to be able to question things like gender-neutral pronouns”.

Abetz labelled Shepherd’s run-in with her university a case of “political correctness gone mad” and said he did not believe the use of non-gendered language should be “mandatory”.

The Labor senator Anne Aly, also on the panel, said she believed it was a “matter of respect” to refer to someone the way they wanted.