Twitter can make a good-faith argument they attempt to remove content that is questionable or that incites violence–they can point to millions of accounts and posts they’ve removed for those very reasons. The ceo of parler can not.
This wasn't one of the ways Parlor was being used, was the ONLY way it was being used, there were not thousands of scientists, mathematicians or people from all the politican spectrum like Twitter there, so any comparison with big social networks is misguided to put it mildly.