It's possible he hid some bitcoins somewhere the FBI didn't get to them, and is now moving them.
He's in jail; he has no access to the hardware the FBI seized (with all his encrypted files on them, and it's hard to unencrypt an encrypted file when you don't have a copy, even if you know the passphrase); and there is no particular reason to move the coins at this time, with Mtgox shattered & the database leaked. It's extremely implausible that it's Ross, now.
It's much more likely it's either Karpeles or a Mtgox insider moving around gains for some reason, or the insider realizes their Mtgox account information is now public and is scrambling to disperse their fortune to less-easily-tracked addresses.
Many of you here have likely heard of Bitcoin, and maybe know something about it.
Earlier today, a story broke that a reporter had apparently tracked down the real Satoshi Nakamoto, infamous creator of the Bitcoin protocol.
This seems like an excellent opportunity to practice our Bayesian updating!
So, how likely do you think it is that this man is the founder of Bitcoin? What do you believe and why?