Boobaloo, good on you for letting those kids know their behaviour wasn't on!
Did you get any response from the parents at all? Did they even notice?

I was once at a park, similar thing happen, but these little brats were pushing my wee one. Grr! In a firm voice, I told them to keep their hands to themselves. Well.... This massive woman stood up, man I crapped my pants!! LOL! But she just came over and told the girls to play nice.

But with that said, I would do it again in a heart beat - a lot of older kids need to be put in their place sometimes. If a random parent pulled my DD up on nasty behaviour I would totally understand (Hell, I would encourage it!)

Hope your little man has long forgotten about it.