The only caveat I would add to this is that while yes, Garland was 100% holding on to him, McDavid was also perfectly happy to lay on top of him initially while it benefited his team with a 5v4 look. He only really starts to struggle to get up after that chance is done and he realizes the play might come back up to him. At that point it's very obvious Garland is interfering with him.
Both guys were bending the rules for their benefit. Letting offsetting interference go at the end of a game is hardly near the top of the list of problems with NHL officiating and if not for the cross check I doubt anyone would even be talking about it. God forbid if Bouchard scores, I bet the Edmonton media are tripping over themselves to write about McDavid's 'veteran savy' to take Garland out of the play.