To play devil's advocate... The shoe came off in his hands rather naturally during the action of the tackle. In the heat of the moment (you just made a big tackle, and then you look down and you're holding... A SHOE?) - what do you do? Considerately locate the owner and hand it to them?
I mean, ideally (and if he had ANY awareness at all, you just drop it). But throwing it back over towards the opponent's sideline isn't the most outrageous thing I can imagine doing when you're excited and celebrating with all that adrenaline going.
It's not like he threw it to injure someone, or ripped it off on purpose, or picked it up just to throw. I feel a bit bad for him b/c this was a TEAM loss (which he definitely contributed to) - but literally, EVERY aspect and unit of the team played a losing effort. The TEAM deserved to lose for how they ALL played.
/devil's advocate/rant