I was at that game. I don't have any strong opinions on Collins either way but that was an unfortunate incident.
Long had made a few errors (one cost a goal) and some fans started to turn on him, standing right behind the goal and shouting some really heinous shit (to his credit he took it incredibly well). After making another mistake (or conceding a goal, I don't remember exactly), Collins gave him a real dressing down and was clapped by a handful of the baying mob, who seemed buoyed by the whole thing.
Long visibly wilted, and at the time it seemed a bit like Collins had callously thrown him to the mercy of the type of fans that get banned on twitter. To be fair, though, Collins may not have realised the extent of abuse that was being hurled, and what he might have been exacerbating. I never saw him act that way towards Long or any of our other players before or after (though I did miss most games that season). As has been already mentioned, he was a decent, experienced partner for Maguire. If the fans hadn't been in such close proximity and Long hadn't been public enemy no.1, it wouldn't have appeared so unnecessary.
That's how I remember it, anyway.