I wouldn't worry about riding on 10-year-old Dura Ace equipment if it truly is lightly used and you find someone competent to check it over. I think they came with a CF fork standard; I'd have a shop inspect that for any signs of damage.
But titanium frames in particular seem to hold their value well.
I think in 2001 Dura Ace shifters and cassettes were 8 speeds -- you'll need to understand that when the chain and cassette wear you won't be able to get brand new high-end Shimano gear but there are still new mid-level Shimano cassettes made in 8 speeds, and other parts you can track down on eBay. If he ever wants to upgrade to 10-speed shifting he could just get modern shifters and and a new rear cassette. Brakes and wheels should be fine.
My only question is the price. $2000 seems high to me - I would think a 10-year Litespeed would be closer to $1200 to $1400, depending on wear.