Hmmm... well I certainly see your point, and I agree it would be a good sketch if they were just playing exaggerated Aussie characters. But I actually think there's more going on here. This sketch is taking place in a university philosophy department. These are professors who specialise in Hegel and logical positivism and they're willing to have discussions about Marx and Kropotkin even though they disagree with them. So it's actually a subversion of the trope, where the characters are supposed to look like dumb bogans, but are actually intellectuals. So under that reading, I would expect them to in fact be rather open-minded and left-leaning, while appearing regressive. So a joke like "No harassing the poofta members of staff" would, I think, be more true to the joke they were actually telling. They're using regressive language with progressive sentiment, like the rest of the sketch.

So... can a poorly executed joke ruin a satire of conservatives? I think it can. I think if you can't thread the needle and stick the landing on such sensitive topics, then there should be a backlash and the sketch should be "cancelled".