no, you've got this backwards.

if it was somebody else, it might not have been funny. if it was charlie sheen, for example, it wouldn't have been funny. but, because it's al franken, and we know al franken's viewpoints, the transgressive humour can operate. i mean, in order for it to be absurd, it has to actually be absurd, and that's largely dependant on the person making the joke.

this kind of thing can operate in just about any context, so long as it's absurd. so, ted cruz could make a joke about socialism that bernie sanders couldn't make; and noam chomsky could make a joke about market theory that ted cruz couldn't make. a joke about a priest or a nun may not be funny if the person is not a priest or nun. &etc. the context of absurdity is really very strongly tied to the speaker or actor. and, a part of the joke is that you'd never expect al franken to actually do that, because you know his politics on the subject - it's a core part of the reason why it's so absurd.

jagmeet singh must cut his beard.