Parler just needs to enforce their own policies and this wouldn't be an issue. They wouldn't need to bend their will to anyone's political agenda, just enforce the policies they themselves espouse.
When will people ask Twitter, FB etc. to do the same?
They could certainly do a world better, but neither were as bad as Parler who basically laid out guidelines but made zero effort to enforce them.
Twitter and FB, for all their failings, appear to basically be operating in good faith (re. removing incitements toward violence). One cannot seriously say that about Parler.