What twitter has or does is inconsequential and almost counter to the whole stated point of GAB. As you mention it though, there is a lot of negative feedback regarding Twitter's handling of extreme views.

Surely though, you see the irony in denouncing twitter for not removing enough posts, when GAB was formed because twitter removed posts?

The thing is, this is generally not about 'one person'. It's just a tipping point. GAB is well known to be the preferred platform for a lot of people holding extreme right view points. They are free to hold those views, but that doesn't mean companies have to agree to do business with them to discuss it.

If the famous cake had the two guys fellating each other on top, you'd have a point. But it didn't. It's just a fucking wedding cake. They didn't ask the baker to be involved. They didn't ask the baker to attend. They just wanted a fucking cake. Their wedding would affect no one but themselves.

The extremist viewpoints being expressed on GAB expressly affect other people, when enacted.

If those people were all getting together to discuss how they're not going to visit Africa or Israel or Asia because they don't like those races, no one would care.

What they discuss (and sometimes act on) expressly affects other people - "keep them out" "kill them" etc.