Shatoshi needs to watch he doesn't become a target for not filing capital gains taxes if he lives in the USA. The IRS would love the press attention on getting him.
that's not how it works. he hasn't even touched his coins, so why would he have to pay taxes on them?
He would have to sell them and convert to fiat in order to have to claim long term capital gains (since he has held them for over a year). Bitcoin is not like a traditional investment vehicle that pays dividends, nor does it issue you a 1099 at the end of the year for interest income.
I hope he's not french : he would have to pay ISF : a tax based upon his wealth even if he didn't sell anything !