I see your bold print and raise you a large.
The corporation may be sold without transferring the NFA firearms.
It is my understanding that if the corporation dissolves the items must be surrendered to the ATF or legally transferred.
If the corporation dissolves with NFA items inside then the NFA items are now contraband as they now have no legal owner......noone but the ATF can touch them. They must be transferred out prior to the corporations dissolution.
If the corporation is sold then the NFA items go with it....unless you Form4 them OUT of the corporation to someone or an entity.
In the OP's situation, since the business is already sold I am assuming that the NFA did not go with it, they are now illegally possessed by your guy. Without a Form4 transfer they are still legally owned by the business that he does not legally own.
Would definitely suggest he get the items to the lawful owner or he could face illegal NFA possession charges.
I would let him know and then back away, you don't want to be anywhere near this if what you post is accurate and didn't leave out key details.