Disclaimer; I'm not a lawyer, and you shouldn't ask for legal advice on internet forums.
I've asked this question to several ATF agents at SHOT Show a few months ago.
Basically, I got this answer; You cannot, according to the Gun Control Act, manufacture firearms with the intent of selling for profit, without an FFL. They were very careful to not tell me "no" or "yes"...typical ATF BS. There has yet to be a court decision (notice how I said court decision, not court case) that has dealt with this exact situation.
The key word is "intent". Based on your description of your situation, no one intended to sell the firearm. Circumstances now dictate a possible sale. I don't see this to be a problem.
IMO, the safest course of action would be to disassemble the weapon, sell off the parts (slide, barrel, trigger, etc.) and keep the completed frame (this is the actual "firearm"). No transfer of a firearm would be involved; only parts. Plus, when circumstances improve, he can easily rebuild the firearm.