Whether Marchand is intending this or not (more likely not) I believe it's related to his smaller stature and passionate demeanor. I believe that affection/borderline homosexuality can be used as an effective polar opposite to aggression/masculinity for obvious reasons. It's not hard to see how a small player who plays on the edge and receives attention from much larger players would use tactics like that to throw off an opponent knowing he isn't likely to win physically. I know the players he licked aren't exactly huge in comparison but this is the best I can guess. I personally loved it (I know this is unpopular) but I've always respected using odd tactics to avoid making things violent.
Last night was a weird game...I'm a lifetime B's fan but I've loved the Caps almost as long. I would have rather watched the Caps blow out the Leafs (sorry GoLeafsGo!!!) and had the B's open on a different night. I shut off the game in the second period and wrote a song instead so I found a way to make it an emotional success regardless