What an odd thing to do
Why wouldn't he just kick it out of the way or something?
He did it intentionally to be get back at the audience, yeah, because he asked them not to throw things and they kept doing it.
But, heck, plenty of rockstars would do something much more rude!
And, it's easy for us to say that it's bad behavior and he shouldn't do it, but would we really be so polite if we had to spend an hour out of our day being pelted with cellphones in front of thousands of people?