He claims to have lost over 4k bitcoins, how is that very good coding skill? (we know he stole it, but how can you call him a good coder when he says he lost it?)
I believe he was a decent programmer. Even if this wasn't a inside job, it doesn't make you a bad programmer that you missed something which someone else found out. Peoples brains operate differently, or may be more skilled. It doesn't make him a bad programmer.
Although, for holding such a large amount of coins, he should of invested in some penetration testing. (He might have) But, as far as I'm aware he coded it himself and probably didn't think it would be a problem checking for security issues himself.
It wasn't a programming bug. The exact vulnerability is described in Brain Eha's upcoming book
Walking the Silk Road (inputs has its own section!!), but the gist was the attacker managed to reset the password on a chain of my emails, and get into the server control panel. There was no programming bug.
Inputs had been penetration tested regularly, and on security-critical projects I regularly spend upwards of $5000 on a thorough pentest by professional security forums.