The coaching mentality is to place ALL the blame for problems on the officials. I think there's 2 possible explanations for this situation described here: 1) the coach significantly downplayed his actions in confronting the officials or 2) the officials, especially younger guys, have been so beat up over the years by this sort of thing that they just shut it down immediately and didn't want to take any comments. I think those of us more experienced officials will tolerate reasonable discussion by coaches who aren't in that particular game, but I have also had Varsity coaches come on the sideline and directly engage me and then criticize me (and even called the assigner 5 minutes after the game).
I don't think its as simple as saying the officials were in the wrong here. Perhaps they need more training, but good grief, I've heard about coaches who've explained to the assigner that they were behaving reasonably when in fact, they weren't.
The other thing that happens in these types of situations is the varsity coach complains the new officials are throwing too many flags. While they may be right about that, they call the next week and complain that they missed calls against THEIR team.