We all know it's just a way for Musk and others to get a really popular social media for cheap. This ban has nothing to do with anything else than that.
Well, to be fair, the law wasn't individually passed by Biden. It was stuffed into a foreign aid bill aimed at supplying both Ukraine and Israel, as well as enforcing additional sanctions on Russia.[1]
It's not entirely clear if Biden thinks it's a good move but honestly I doubt very much he has his own opinion on this as it is.