Right - because if it were you, at 18 years old, you would behave in a completely respectful and dignified manner, right after winning the biggest game of your life on an international stage.
The Swedes were pissed, the Americans gloated, it got a heated and some punches were thrown - big deal. Adults in the NHL behave far worse. Dale Hunter comes to mind and there are plenty of other really bad examples.
Who cares when you lose? Everybody does. I would have punched somebody too if I was on team Sweden. I cannot imagine how fired up I would be in that position as an 18 year on either team. If I were on team USA would probably drop my pants and give the whole damn crowd the brown eye.
I'm not saying it's right - that's just the way it is.