Screaming evangelists are okay??

Okay, let me get this straight, an evangelist wearing a sandwich board and screaming at the top of his lungs about the bible and salvation and all that is okay, right in the middle of a beautiful day on Downtown Crossing? I mean, it's okay for him to ruin my attempt to get away from the drudgery of the office and get some time to myself?

He's allowed to that?

Why?