Might also be a factor that that was the same time that Dickenson started taking on GM responsibilities. 12-6, 8-6, then 12-6 again the first three years Killam took Assistant HC. Then Dickinson took on the GM role and now they've gone 6-12, 5-12-1 in the two years that follow.
The recent downfall could be just as much be a new GM not doing very well in his expanded role and scapegoating all his staff this summer to absolve himself.
Dickinson himself is one of the most animated coaches out there. Would it not make sense that those working under him would do similar?
That said, I do think your point about his sideline comportment is valid. Fortunately though Hervey's a little more seasoned now and has gone through a bit of that already with Maas and Claybourne, so he may be a bit better of a mentor to help guide Killam through that. If they think Killam's got the best mind for the game of those available, they can work on the other stuff.