It's similar in that sense to platforms (I'll stick to that term as I don't think your distinction is meaningful or helpful) like Facebook, Twitter and Parler etc., which also allow private messaging as part of their services or include closed groups which are not accessible by all. The very forum on which you've posted has rules about acceptable content which you signed up to before you could post - nobody twisted your arm, and you were free to take your views elsewhere if you felt them too restrictive.

Are you seriously suggesting that these platforms should be a free for all because of some misplaced adherence to libertarianism?

Anyway, my intent with posting the OP was to draw attention to the degree of organization and prior intent among the insurrectionists. The argument about Web privacy is a different issue.