If he sold voluntarily at a loss (to a relative, say, at a discount) when he could have gotten FMV, only then a gift tax return would come into play. If he can't get any offers any higher, then he didn't "give" anything away.
If you haven't already, you may want to use worksheet in IRS pub 590, appendix B to see if it comes out the same. Apparently one of the wrinkles involved is if covered by retirement plan and the worksheet itself is 3 pages to determine deductibility/taxability of soc sec benefits with IRA deduction. Just a thought.