the theory works for me, that Kerry was less than honourably discharged for his actions, going to Paris and negotiating with the enemy when he was still a commissioned officer and of course without authorization from the US government
he deserved greater punishment, his behaviour was arguably treasonous, but Nixon likely didn't want to make Kerry a martyr
there was some speculation too that a LHD precludes one from holding office as well....
Kerry got lucky with the Carter amnesty
I also remember right before the election that someone who worked with or under Kerry in the Navy was going to spill the beans on Kerry on Free Republic, the suggestion was this person either knew personally or worked under a Navy commander who knew that Kerry was less than honourably discharged but couldn't say anything unless Kerry consented or he would be breaking the law, and the Swift Boat Vets told him to stand down anyway
the lefties wouldn't have gotten the significance anyway