I don't mind Parler being deplatformed as long as similar standards are held for others. Given that Facebook was also a major contributor to the organizing of January 6th I think it makes sense people were asking for their deplatforming as well. That never happened though, and goes unanswered w.r.t. the logic that you've shared.
Deplatform all of them, right? How about the telephone companies that transmitted their conversations? Or the hotels and AirBnb for housing them? And the restaurants that served them? And Uber and airlines that transported them? And the sporting goods store that supplied them? And …
I mean, I'd prefer deplatforming not being an option, but the momentum for it as a tool is far too strong. It's far more expedient that the folks that are championing that as an option also have to use it on institutions they're associated with or favor for similar actions.