If you read the testimony of the perpetrator, he said, if I understood it correctly, that he didn't touch the helicopter but merely raised up on his toes with his arms straight up, as one does standing under the blade disc. Now all that is needed is simply to back up a bit, when disaster is guaranteed...
Is there any point to continuing to second-guess the actions of the pilot? Some here seem to think that a rotor brake is some marvelous device that you use to just stop (Eeerk!) the rotors "just like that," when really it still takes some time for motion to cease. To have some angry loon poised on tip-toe under a slowing, drooping main rotor... that doesn't sound like a real smart idea to me.
Given that no one was injured I think we can just take it as read that the pilot took a course of action that was essentially correct in coping with a person who was being criminally foolish. Otherwise the judge would have come to a different verdict. I cannot see how a pilot could have anything much to say against the action this pilot took; sometimes we really do have to take sides.