Thats interesting but in the article you cite, it states, "Recently the case has been highlighted as a potential precedent to treat online communication media like Facebook as a public space to prevent it from censoring speech. However, in Manhattan Community Access Corp. v. Halleck the Supreme Court found that private companies only count as state actors for first amendment purposes if they exercise “powers traditionally exclusive to the state."we’ll see, there’s precedent that private property becomes a de facto “public square”
Marsh v. Alabama - Wikipedia
en.m.wikipedia.org
So not looking good if that's the approach. A more likely approach would be to claim that Facebook, Twitter, Apple, etc., made these free speech constraints at the behest of the government if there was such proof. For example, if hypothetically Apple removed the app based on threats of repercussion from members of Congress. I rather doubt that scenario though.