Separating the art from the artist is really only a thing when you can enjoy said art without benefiting said artist. Otherwise, there's not really a separation.
Take NASB, for example. John Kricfalusi is an absolutely wretched human being and a known sexual abuser. But there wasn't much of an uproar when Ren and Stimpy got into Nickelodeon All-Star Brawl, because Kricfalusi doesn't see a cent of the money, as he doesn't own the rights to the series. Likewise, if in a hypothetical scenario Disney made a platform fighter, I'd still be pushing for Woody and Buzz to be in despite being made by John Lasseter, and that's again because he wouldn't see a dime.
Hell, I know some folks who had held off from playing Dragon Quest but recently finally did so because the dumpster fire of a composer finally died, meaning they could enjoy the games without either pirating or lining the pockets of an alt-right war crime denier and LGBTphobe.
And that's why the issue with Rowling and the Wizarding World isn't nearly as easy to "separate the art from the artist." Any purchase of a product under the Harry Potter license is directly paying one of the most famous and infamous anti-trans bigots on the planet.