> Even on HN you can still see claims that USA is a "free" country where anyone can say anything about the government, without consequences.

The first amendment applies to public spaces. Not private conferences which are invite-only. You're on an anti-U.S. tear in this discussion but lack understanding of the basics.

For the same reason I can't show up at your office and start handing out religious materials and/or pornography (take your pick) to everyone showing up for work and claim it's a free speech issue and my right to do so.

As someone else pointed out below, this exact argument was used to ban apps lacking "correct" moderation from the app stores a few years ago.