If there's a drunk guy trying to start fights in your restaurant, you boot him out the door immediately for being a safety hazard and overall reflecting poorly on your business. I don't think any reasonable patrons will see that and think "Wow, they just kicked that guy out because they didn't like what he was saying, it could happen to me too, better get out of here".

It's a similar (digital) situation here. Parler is (was?) actively refusing to moderate their platform to prevent a literal insurrection.