"Hate Speech" as you call it, no matter how distasteful you may find it, is protected speech under the US Constitution, and thus (if also not a threat of violence, doxxing, or similar) is permitted on Gab.

I have no problem with platforms allowing any and all speech, since it actually just allows stupid speakers to beclown themselves.

Free speech is the most liberal idea there is - as Voltaire famously said, "I may disagree with everything you say, but I will defend to the death your right to say it."