I don't live in New York, but in my city any loud or disruptive noise is against the rules and can be fined. I think this is a good policy consider the purpose of the subway. However I do wish there were more public places where people could freely be loud and obnoxious. But the subway is not an ideal forum for this.

I don't have any problem with the guy personally, I think he is ethically justified, considering his poverty background. However I don't think this is a tactic that should be emulated by well-educated entrepreneurs. Breaking important social rules to make profit is rarely beneficial on the whole.