LOL. Dropping the weight after every rep was kind of idiotic and douchey. Even if I was pulling 585 lbs, I would set it down as quietly as when I picked it up. There's no need to slam the bar down like that, it's just for show or something I guess...??
That being said, the other guy WAY overreacted. Kindly and quietly giving the kid some tips on proper deadlifting form would have been more constructive and helpful. And I agree with you Al, kicking the weight out of the kid's hands was fucked up and could have really hurt him.