I'm not an expert in the entire IP landscape, but I suspect this might not be a copyright issue at all. The problem is the brand (how George would hate that phrasing) is being appropriated. If you paid an artist to draw a picture of Keanu eating donuts for an advertising campaign there would be the same issue.
If anything this ends up being a partial defense of AI, given that the issues raised are neither specific to AI nor require additional laws to seek redress. It is hard to determine how much of the article text
>That training would, by definition, involve making "unauthorized copies" of "Carlin's original, copyrighted routines"
...is a quote from the lawsuit. It is certainly not clear in a moral or legal sense whether training constitutes making an unauthorized copy. That is the big issue to be decided. Having an opinion and declaring it does not make it true. People are doing that on both sides already.
It should be noted that in addition to the legal issues, comedians have their own culture which is separate from the legal definitions of acceptable behaviour. The tolerance for reusing ideas is considerably lower within that community. Many things that are perfectly legal might render you a pariah to that community.