I'm of a split mind about protests, but ultimately come down on the side of finding the declarations about "illegal" protests generally bad.
On the one hand, I find a lot of protests to be hollow and run by somewhat stupid people who undercut their own causes (many of these pro-Palistinian ones fit into that box). They also obviously can regularly spill out into mayhem and nonsense and attract some real bad actors.
But it's also worth noting, creating incentives to suppress protests seems like a step toward suppressing the speech that undergirds the act of protest in general. Part of our country's national mythos involves people hiding their identities and destroying private property. We even named a right wing movement after it about 15 years ago. And as annoying as it is, plenty of good and honorable protests inconvenience bystanders. People were late for work because of Rosa Parks. Locals probably wanted to use the Edmund Pettus Bridge one Sunday, and found it occupied (also probably found the blood on the pavement the next day unsettling). These are realities of free speech in our nation.
That doesn't mean you just give a free pass to illegal acts, though you should handle them as makes sense. But creating this disincentive to allow a certain kind of free speech would move us farther down a road people who actually care about rights should be worried about.
Blanket statements about disallowing protests is stupid, unconstitutional (imo), and contradicts the values of a lot of people who voted for the current administration. In fact, many right-wing voters complained about bad steps being taken in the wrong direction under the previous administration regarding that very thing.
I don't like Neo-Nazis, but on principle I will support their right to a public forum. Actually, a while back I thought about it and decided it's really better if all the idiots are allowed to say what they're really thinking. If you're a racist restaurant owner, I don't want the government to shut down your speech or your restaurant. In fact, I'd rather you just put a sign on your door saying "I'm racist, only whites can eat here." That way I know exactly which restaurants to avoid, choosing not to give my money to them. If the government silences them, how do I know which restaurant to stay away from?
Anyway. The problem with a lot of the pro-Palestinean/pro-Hamas/anti-Semitic protests on campuses was not their free speech, it was their chants for violence--which is not constitutionally allowed, in my understanding--and in some cases actual violence.
So the message ought to be "Protestors who shout threats toward others, veiled or overt, won't be tolerated." What Trump's tweets, or whatever you call them, that were reposted here came off like, was "No protests allowed at all."
Given everything I know about him, I suspect that's not what he means and certainly not what he'll try to do, but the messaging is bad, and wrong-headed. It's also likely with him that he's merely vying for popularity points with a segment of his base, in which case, it's still bad, and wrong-headed.
I maintain that Trump is all the ammunition that Trump-haters need to cry foul and gnash their teeth. I don't know why the Left wastes their time lying about stuff. Everything they need to criticize him, he does for them for free.