It wasnt sarcastic. It was a sincere response to thumb their nose at Montreal's fans who booed. It was out of respect, but more out of respect towards what the anthem means. And as Panger just said it was a sign to show Montreal fans what they did was unacceptable
were they cheering the anthem because of how much they respected Montreal, canada or the canadian team, No. [though im not implying they DONT respect said topics...] They cheered it to show that booing the anthem is a stupid tactic to "get at the visiting team" as some put it. And that the anthem has meaning, and shouldnt be used as a ploy to "get at" said team.
You and I have the same view on national anthems and the respect they deserve. However, I think you have a little more faith in the inherent "goodness" of people. I hope it was as you mentioned above. I'm just slightly skeptical, especially considering they were told not to boo and it's playoff hockey, i.e. show no mercy. Oh well, I hope i'm wrong.
Hell, my Sharks are in a great spot, it was finally a beautiful day after 4 days of rain, I'll go with the optimist side and accept it like you said it. Great move! Classy! Let it be a positive reflection of the American people especially given the fact that most of the world has written us off.