Whether he was a good or bad coder. He didn't update or maintain MtGox regularly. When hackers stole millions in
BTC from MtGox. The theft went undetected for months.
He never invested time or energy into the infrastructure side of the exchange. He was always way behind. Even on basic upkeep, backing up data and maintenance.
Well, shoot....I never said he was a perfect coder or couldn't make mistakes. And yes, I agree with everything you wrote about him being a sloth (and also a control freak from what I've read). If I'm not mistaken, he didn't let the small staff of Mt. Gox do much of anything, certainly not much of importance.
Karpeles also didn't create the exchange, which I'm sure you know. He probably thought it was just fine when he took possession of it and continued to pay attention to his cat and manga and Mt. Gox's coffee shop rather than security and everything else that goes into running an online exchange.