I went and looked at an old copy of MILPERSMAN And found something I had not been aware of. In some cases an officer is allowed a "resignation for the good of the service to escape a general court-martial." What we would need to see now is Kerry's resignation letter which would state that reason per the manual and would be in his records. As far as I know, every officer, active and reserve, who leaves the service without retiring or being forced out has to submit a resignation letter.
Interesting perspective. That might just be possible, as the military has never wanted the publicity of officer courts martial, except in the most egregious of circumstances. I would think, though, that those kinds of records would be releasable under FOIA. Not sure if that's been tried, but I assume it has. Time is running out though on this one.