A similar thing happened on a SFO->JFK flight I was on. Only a couple of us paid for exit row seating and there were many empty seats which filled up shortly after take off. But there weren't any "college hooligans" and everyone got along fine.

Are you more annoyed that the seats were filled by pax that didn't pay extra? or that they were rowdy college students? Personally, I would be more annoyed at the latter. Exit row seats are normally full and I'd pay the extra fee just to guarantee I got one if it were a free-for-all (ie. Southwest).

I hope it works out for you.