Yes, he is. I doubt if that account has been used by him for years tho. IIRC, there was one login to say he wasn't Dorian, but we don't know if that was actually him.
If you look at the history of digital money starting in the 80's, you'll see a common theme. They were all squashed by government intervention (mostly USA). The founders often ended up in jail.
Satoshi would have known this, and obviously wanted to be safe while these thugs had an incentive to make a spectacle of him in an attempt to kill bitcoin. Sooner or later, I think that time will be over, but even then he's a big target for thieves with rubber hoses, ransom demands, etc. If I were him, i'd want to mix my coins before coming out of hiding, but then I'd be affecting the ecosystem/price. Tough decision.
He wasn't much of a coder, so couldn't contribute much code once professional coders got involved. His expertise was in the incentive area, but if he posts anything up to his standard in that area he'd be outed pretty quick, so he stays silent ... err ... until recently maybe
I think it's obvious he'd keep tabs on bitcoin, so he'd have unconnected accounts for reading purposes.