The thing is, this doesn't actually matter. This service wasn't being used to "freely assemble" (as outlined in your source), it was being used as a tool to facilitate insurrection.
This clear and present danger was obvious, and places the imperative on supporting services to question whether they want to aid and abet sedition.
This isn't just about Parler specifically. The point is that with any of these deplatformings, it is manifestly untrue that the platforms can do whatever they want.
This clear and present danger was obvious, and places the imperative on supporting services to question whether they want to aid and abet sedition.