His investors and board hired him to win, not to pick a principled hill to die on. Martyrs are cheap and nobody making investments can afford cheap things. The irony is Parler positioned itself as less radical than Gab, and it was that very position of bargaining with its platforms is what killed it. How can 4chan, Gab, and the even darker parts of the internet manage to persist online with hardly any money, but someone with Mercer level backing can't keep a site online? The lesson is an example of things we already know, which is that anyone who needs platform permission do to a disruptive startup is already dead.
We absolutely need alternative platforms, and our societies need tools that can survive popular histrionics. Getting owned by some sanctimonious prick at Amazon is not pro level play.