I dopn't find the boy and his family rude at all... I find the guy that yelled to be a HUGE D-bag and I personally would have been happy to tell STFU...LOL of course quietly not in front of my boy!!
Seriously a spontanious cheer on the golf course for a bird, an eagle an ace a whatever is not rude or out of line. I love golf but things like this are part of the reason so many people are not interested in the game. lighten up boys and enjoy the game.
and for the record, i play for money vitually every round i play and occasionally for a decent amount...that should change nothing about how you treat others or a child celebrating a legit cause!!!