...but to be fair, he did come out with a Tweet a few weeks ago in full support of vaccines, and even downplayed the minor risks of side effects.
Who knows why the powers that be at SNL chose Musk. Maybe they thought he'd be an interesting choice, especially since he's done so much with Tesla, SpaceX, the The Boring Company tunnels, etc., when major car manufacturers and oil companies had repeatedly tried to shut down the idea of affordable and mass-produced electric cars and he doesn't use the traditional dealership model to market and sell his vehicles, NASA traditionally had a lock on the space program, etc. He also tends to be outspoken and ends up in the news every several months.
That said, he's hardly the first somewhat controversial figure to be on the show. Donald Trump certainly wasn't a popular choice, and way back when, Sinead O'Connor tore up a picture of the Pope after exclaiming "Fight the real enemy!". When Andrew Dice Clay was to host, at least 1 female cast member boycotted that week's program completely. There have also been a handful of guest hosts or musical acts that were banned from ever returning to their stage, either because they were difficult to work with and treated others on the show poorly, or because of something that occurred during their time there.