End of Game Punch

[RochesterRef]

I was doing a Modified game and it was the very last play of a game in which the home team was on the receiving end of a very sound beating. The visiting team just ran a little dive up the middle to run the clock out. There was a fumble and as the linesman I ran in to uncover the pile. We scraped kids off til we got to the defender who made the tackle and the runner. The tackler went to get up, then laid back down and gave the runner a punch in the stomach. Not a wind-knocked-out punch, just a frustration punch. I flagged him for PF, and said something to the effect of "are you kidding me? Especially when I'm standing right here?" and the kid replied "I was just trying to get up." Game is over, defender's (the one who threw the punch) coach comes up to me. Asks me what I had, since the game was over we didn't report the penalty. I said #20 punched the kid in the stomach. He grabbed his player's mask and said, "you're not playing in the next game" and thanked me. Good coach if you ask me. The reason for posting this here is I'm wondering what you all think of how I handled it, and if there's anything I could've/should've done differently?