He'll be gone.
My guess is it was a couple drunk Packers fans and obviously, Mackenro's bro Mackensie plays for the Vikings. They probably got to talking, both parties being drunk, and when the frat boys realized who he was, they probably started making jokes and talking crap about Mackenro's brother, a Viking. Mackenro, being intoxicated (probably) himself, was more irritable than normal, but put up with their chiding.
BUT-- when the conversation turned from harmless jabs to personal blows, Mackenro could take no more. The frat brothers start taking shots at Mackenro, "Your brother has been in the NFL for a whole year now, what happened to you? You're still in college, and on your 3rd one no less. What gives? Not good enough to make the league? You not as good as your brother?"
Mackenroe couldn't take it, as this has been his biggest insecurity for years now. Buttons were pushed. He reacted.