I'm not sure having his chief military advisor walk over with him was smart (and I wouldn't have done it, and I wish he hadn't done it, because it made a stupid photo op look even more idiotic), but I don't know that it means the military was involved in clearing the square.
Having said all that, and setting aside the tear gas and military stuff: For me, it all hinges on whether the protestors were peaceful or not. If they were peaceful, then you and I agree there was a problem.
Then again, the night before, peaceful protest turned into arson of a 200 year old landmark, among other violent and vandalistic acts. I can see why the park police would want those people to obey the curfew, since all indications were that what happened the night before would happen again.