What's the point?

So MLB has fined Ian Kinsler, shown here on card number RD-2 of the 2006 Topps Rookie Debut set, and suspended him for one game. The punishment stems from the extra innings game against the Yankees on Friday.

In that game Kinsler was ejected in the tenth inning for arguing balls and strikes. That's not what got him in trouble though. In the thirteenth inning Nelson Cruz hit a walk-off homer run to win the game. Ian ran on to the field with the rest of the team to celebrate.

Apparently there is a rule about an ejected player returning to the playing field. I understand the rule and the need for it. Well, I understand it most of the time. You can't have a player with nothing to lose coming back onto the field after being tossed. Such a player might want to effect the outcome of the game or continue his feud with the umpiring crew. Not cool.

What I don't get is why Kinsler got suspended in the first place. Sure, he came back on the field and that's a violation. He wasn't attempting to effect play though - the game was over. He also wasn't restarting his disagreement with the umpires - he came on to celebrate the win and did only that.

So fine him and move on. Why suspend him as well? I just don't see a reason to throw the book at him or any player in a similar situation.