Not inherently, but since that was the rule for this public event, he should have obeyed it. But since he obviously didn't intend to, I think it is legitimate for the cops to escort him away from the mike.1. Asking more than one question does not mean they should be intervened by police
If they had just tased him while he was asking the question, that would have been premature. But they didn't - all they did was try to usher him away, and then responded more forcefully when he shoved them away.
So? He was being a public disturbance.2. The rules of the event are not rules of the law
And how then, do you propose the police deal with this guy? He was clearly fighting them every step of the way, and wouldn't even let them cuff him. He wouldn't allow them to take him out until after they tased him, at which point he started cooperating - note that before, he was fighting them every step, while afterwards he was walking with the cops holding on to him.Tasers should only be used if they are a danger - the guy clearly wasn't and it was the police who were the danger if anything.
I suppose they could have kicked him, or something, probably causing even more damage, or they could start carrying bottles of chloroform to anesthetize troublemakers, but they didn't have that option at the time. I'm still waiting to hear a viable option for how you force someone to cooperate with you who is physically resisting without hurting him.
EDIT: And for those of you who wanted documentation on the fact that he cut in line, here it is. According to Sen. Kerry, "He barged to the head of the line, this wasn't someone who waited patiently for his turn and asked a question."