In my opinion it doesn't matter whether the photos were scenic or nude, these people demanded negatives that were not theirs and had the audacity to raise it at RKs wedding. If his former model asked him in a more appropriate manner and at a more reasonable time, I'm sure this whole issue would have been more amicably resolved.
For what its worth, I would react in the very same way as RK [I'm a Kennedy too so maybe thats why]
I think this guy is actually punishing his wife for the modelling by making war with RK. The guy is either a prude, lacking in self-esteem or sexually dysfunctional [or all three] and he is certainly a bully. She just wants it to end, I'm sure she is getting plenty of hassle that RK does not hear about. The higher value RK places on these photos, the more this guy wants them off him and the more satisfied he will be if he gets them in the end of this.
Few photographers would ever give away their negatives for free. Few non-photographers would understand why not. Most women non-photographers would take the models side in this argument.
When in a lose-lose situation, taking the high moral ground is always a good thing to do. Losers that lose with dignity in the face of a bully always come out the true winners.
Only RK knows what he wants to do. I think he and his wife are due an apology for having this raised during their wedding.
Personally I would ask this guy for a small donation to charity to cover the cost of the film only. Get him to pay it, not her as he is the one thats at issue. [ http://www.fotokids.org/en/home.html would be an excellent charity to choose ]
I would place a low value on these photos/negatives so I think you should destroy them, they are destroyed already in reality because they are tainted by this aggravation. Give your model an envelope with them shredded.
I have seen RKs photos on his personal website, there are some really great stuff there. Models come and go, your next one will be even better. I wouldn't give this guy the satisfaction by prolonging it.
Rise above it.