Kirk did denounce the violence:
Kirk “denounced” the audience member’s remarks because, he told the man, “you’re playing into all their plans and they’re trying to make you do this.”
“So, no, I – no, hold on. I – no – stop, hold on,” Kirk told him. “Now, I’m going to denounce that and I’m going to tell you why. Because you’re playing into all their plans and they’re trying to make you do this. That’s OK. Just hear me out,” he urged.
“They are trying to provoke you and everyone here. They are trying to make you do something that will be violent that will justify a takeover of your freedoms and liberties, the likes of which we have never seen,” Kirk fear-mongered.