He was too tall to hang himself.

"If I try to hang myself... Wouldn't it be awkward? I'd have to stand on a chair first, banging my head on the roof, and then I might as well end up standing. I'd bang my head in vain," he thought as he erased the idea on his notebook.

If he was going to do it, it had to be less awkward than accidentally ending up standing in the middle of a room.