I understand the technical question. P.K. did unquestionably knock the net off. If the refs called every infraction by the book, it should have been a penalty, or rather in this case a penalty shot. Yet with the tolerance level the officials have shown, it shouldn't be a gigantic surprise that this was overlooked. The penalty was written into the rulebook to prevent defenders, caught in a mad scramble around their net or trying to play an odd-man rush, from blatantly going right at their own net and pushing it off its moorings to get a stoppage in play. This was nowhere near the case in this instance, the puck being behind the net and P.K. being in a good position to retrieve it first. There was no clear and imminent danger of the puck being pinballed into the net.
Further, if P.K. did knock the net off, intentionally and strategically, he should be up for an Oscar nomination. His actions are all legitimate in terms of hockey. He spots the puck behind the net, decides to go to the left of the net, tries to bank around the post on his one skate, and knocks the net off by brushing it with his shoulder while reaching for the puck. The whole time, his eyes are trained on the puck, not the crossbar. In similar instances, you usually see a Chris Phillips or a Barrett Jackman turn his back to the play, grab the crossbar and lift and push. Then act as if nothing happened. P.K. was playing hockey, making the proverbial 'hockey play' when he knocked off the net.
Meanwhile, Milan Lucic again was caught spearing Alexei Emelin, for the second time in a month, and a couple weeks after the egregious infraction against Danny DeKeyser. Barely a peep is heard about that. Dave Hodge brings it up with Darren Dreger on the "TSN Drive" radio show, and the latter just chuckles and dismisses it as an inconsequential spear. Of course, this latitude does not exist in the rule book.
Rule 62 - Spearing
62.1 Spearing - Spearing shall mean stabbing an opponent with the point of the stick blade, whether contact is made or not.
62.2 Double-minor Penalty - A double-minor penalty will be imposed on a player who spears an opponent and does not make contact.
62.3 Major Penalty - A major penalty shall be imposed on a player who spears an opponent (see 62.5).
62.4 Match Penalty - A match penalty shall be imposed on a player who injures an opponent as a result of a spear.
62.5 Game Misconduct Penalty - Whenever a major penalty is assessed for spearing, a game misconduct penalty must also be imposed.
62.6 Fines and Suspensions - There are no specified fines or suspensions for spearing, however, supplementary discipline can be applied by the Commissioner at his discretion (refer to Rule 28).
For even novice hockey fans, it is obvious based on a cursory reading that Milan Lucic should have received a major penalty for his cheap, undisciplined spearing of Alexei Emelin. If the refs missed it, the NHL 'Department of Player Safety' (and by now it really needs to be put in quotes, since Alexei Emelin is definitely not being safeguarded by the NHL) should have reviewed the play and taken further action.
That this hasn't been the focal point of the analysts on the various shows covering the playoffs is further proof that the old boys club is alive and well. There are oodles of former Bruins on HNIC, on TSN and Sportsnet, or "gritty, energy" types who are out to justify their previous career. The NHL press corps is so inured to violence and lawlessness, they're like fish who can't tell that they're wet. They're drawn to a P.K. story like moths to a flame, but continue to give reprobate Milan Lucic and his cohort an indulgent benefit of the doubt.