Currently the majority of our culture feels acting on racist motives are bad. An individual who internally is racist, posts racist things on the internet is only bad when they act racist towards someone.
If a platform blocks someone from posting a non individual targeting racist post and it gets blocked on Facebook, that is similar to someone posting something against a religion and it getting blocked because the moderator is religious, or posting something anti American and the site moderated by an American blocks it because they disagree with the content.
As much as we might all hate it, the lobbying for an open free internet means giving everyone the freedom to post their thoughts without backlash. Imagine If the civil rights movement took place during the Information Age, Amit of people would have compared promoting anti slavery content on posts to anti vax information today.