The problem is, you'd have to get a proper hub (I personally could not sleep knowing I sent some kid off on a loc-tite'd freewheel and charged money for it) - and new wheels/tires at least. That's already more money than the bike is going to be worth (unless maybe you can find those parts used somewhere). Then people are going to look at that electroforged frame and one piece crank and say "no way".
Well at least if they've been reading any of the threads i the singlespeed forum here...
You'd really have to pawn it off on a sucker.
I think simply cleaning it up and keeping it as a ten speed would result in a more saleable bike - plus it'd be less work.
I mean he only paid $5 for it, really he could have turned around and sold it as is for $20 pretty quickly. After cleaning up the chrome and adjusting everything, he should have no problem selling it.