All questions of "art" aside,

No matter what else he is, once he charges admission and gets up on the stage he is a vendor with a product and a target marker.

Within limits determined by the legal system, vendors have a right to offer any product their little hearts desire. However, bendors ignore or dismiss or belittle or ridicule the reactions of the members of their target marker at their economic peril.

It is without doubt the right of the vendor referred to in Nemesis' first post to decide that the purpose of his performance is to make people "think," or mad, or even mad enough to leave to concert. The success of his presentation will, of course, be a function of the size of the audience at the end. But if he "succeeds" who wants to listen to any whining on his part or the part of his defenders?