It might be a matter of his style of photography. If he is just a friendly chap who take good picture interact with the subjects after the picture was taken and offer to send them if they so wish, smile a bit, say hi to the barista express why he takes picture I think its less of a problem.
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In short a matter of social skill... Lack of it .
I feel the same way. It reads like he had a "Defensive Response" already for anyone questioning him. He had a "Point to make". Which worked to his own harm and hobby in my opinion.
He went out with a attitude of fighting for "His Rights". Which he has, but it sounds like he was rude when approached about his photography.
Maybe he should have become a part of Church Street by patronizing local coffee shops and the like as a back research and to allow the locals to see him as a regular guy. I know that is not always available. So, having good social skills is required. But, having a prepared defense is not the best way to blend in.
Perhaps, the street photographers should be friendly folk without being a pulpit for 1st amendment rights, unless it really necessary. Why jeopardize everyone else's rights, just because "you" want to "prove" a point that doesn't need to be proved. Unless you want to limit your rights more (like this guy did to himself). Yes, he did this to himself, by not reacting in a more friendly manor in the 1st place. He had something to prove to those people on Church Street, and he lost, because he was rude. He might have been 100% right technically, but, he had no social skills to go about in the right way. Which would have allowed him to continue to take photos.
As a sidebar:
I agree that if he used a standard lens, and be more open, instead of a telephoto lens and being stealthy, he would had much more interaction and perhaps develop a friend or 2. When I go out. I use my 28 or 35, and I will wind up talking to at least one person in the hour or so I am taking pictures, typically more. (Not saying I have the answer either, but sugar gets more results than salt).