I watched the video. I don’t think Costa’s attitude was really appropriate, neither was Trump’s. He shouldn’t have continued to keep asking questions, and Trump shouldn’t have been barking back the way he did. Neither one of them acted like adults. Costa was unprofessional and escalated the situation by not letting Trump finish the answer to his question before asking another one.
As for the making contact, I think that is completely overblown, I didn’t see any intention there, and the intern shouldn’t have reached across his arm and his body to take the mic. I’ve watched it several times and his hand was coming down as she reached across under it, it was accidental.