The league needs to clean this stuff up. In the end, I blame this on the league and it's "playoff reffing" which is neanderthal and an insult to basic Rule of Law (in a sports context) and consistency of the sport.
I didn't watch the game, but generally, some action begets another. As a prime example, when Kadri was suspended in his final game as a Leaf it was preceeded by him taking a low hit to the knees if I recall correctly, right at centre ice without a call and then a hit on Marleau hard into the turnbuckle, again, without a call.
So Kadri wrongfully lost his cool and paid the price for his infraction while the Bruins got away with far too much. When you let some blatant acts go, players stew and act out.
Call the damn games straight or be forever known as a goon league that sports bettors will distrust and only MMA fans will be interested in. Give me hard hitting, intense hockey with the odd scuffle when someone crosses a line, the game shouldn't be players constantly going over the line, mocking the rulebook and refs never punishing.