I'm going to second the "definitely a nerd", since not only did he make up an arbitrary rule, he even altered his behavior to be logically consistent ("well, matches can happen in random choice, so I can't disallow those ..."). That's pretty cool.

Hey, definitely a nerd. For fun he finds code races in Redis/Bayeux server failover. Also he fights in clubs, bashing his friends with sticks. And designs card/board games.