The climate change deniers have won

Don't apply laws that you don't understand.

It certainly is a screed - you can practically feel the spittle as the guy expresses indignation that anyone could possibly disagree with the teachings of his own church. Cohen seems to have made no effort to understand what the other side says, but is still sure they must be evil and wrong to say it. In short, he's "projecting".

That said: it's "Godwin's" law, and that law is about comparing one's opponent to Hitler or the Nazis. Comparing one's opponent to a Holocaust denier isn't quite the same thing. I agree that invoking Holocaust deniers, just like invoking Hitler, is in this context a sign of desperation and ignorance - it's something one might do when you have no good arguments against their position, as a substitute for actual thought and engagement. So I do agree that people who shout "denier!" probably ought to be shunned and not engaged with, but if we're going to call that principle a law, it needs a different name.

https://en.wikipedia.org/wiki/Godwin's_law