to metro= OR
he just got scared because of orochimaru's killing intent and knew he couldn't beat him by spamming chidori right off.
Too many maybe's for things we don't know, what we do know is that his personality is about 50% obito, with the slacking off on being on time, and the cockamaime excuses he gives for it. He's trying to live out his life the best he can while trying to live things the way obito might have. (caring for friends, bending the rules a bit, enjoying life, slacking)
No need to guess at things we haven't been told yet, or how they happened, or the psycological effects its had on him. Since the manga laid out his reason for not fighting orochimaru there pretty plainly.
"Knowing is not enough, we must apply.
Willing is not enough, we must do."
- Bruce lee