I belive the situation was way more accelerated by OP not keeping his cool than his age, even though a complaint should be filed to UA anyway.

I have never been treated even close to that bad by a GA, and I am 21 (but doesn't look 17) with a mere 1P.

Given that OP is a 1K, shouldn't he be on the very bottom of the list of confirmed passangers getting kicked of the plane due to plane change?