That's a pretty controversial stance if you actually stop and think about the underling implications though; freedom of expression is internationally recognized as a fundamental and inalienable human right (comparable to the right to work or the right to life), but nevertheless it's considered generally acceptable to limit expression on privately owned platforms to only within accepted ideological views - if you took the same stance on other human rights, it could easily be used to justify any manner of atrocity.
I mean it may seem tame with this, but if, for example, Steam decided (for whatever reason) that they wanted to delete anything which promoted racial equality or referenced any religious view or appeared to advocate for LGBT rights, you can surely see how it would be a problem, even though the only difference between that and this is what the people involved believe is right?
I understand that a company has to look out for it's bottom line (and it's reputation matters for this), but you can't seriously believe what they're doing isn't immoral if they do something which is by all accounts wrong to do generally, just because the people they're doing to specifically are currently socially acceptable targets?