Separating the art from the artist has never been about avoiding the moral complexities of supporting bigots and fascists (financially or just keeping them in the Zeitgeist). It is that authorial intent is not relevant to personal interpretation (aka death of the author). So yes, you can separate the art from the artist but that’s an entirely different thing from what is being argued here.

If you want to argue as to whether their works should be consumed at all - paid for or not - we should absolutely not be separating the artist from the work. There is little value in them that can’t be found elsewhere and capitalists see the enduring popularity of „that fucking book“ and keeping forking over money for the IP, whether people pirated it or not.