It's not like they're forbidding protest. They're forbidding mobs from forming around the President. There are still a great many forms of protest people can and do use. I don't think Bush is so stupid that the public's opinion can be hidden from him by keeping protestors away on the rare occassions where he travels in public. I know that when the President comes to Pittsburgh, they often shut down the entire highway for a few minutes while he rides past. They likely stop flights at the airport to let him land. Etc. etc. I don't know what the law says though, maybe it really is against the law.

The reasons given for said actions are obviously false, and it tends to make people think they know they're crossing the Constitution. --El Mariachi

Obviously false in what way?