The general under less than honorable conditions is the next worse one. It does not require a major hearing and judgement, which would have been reported or recorded in public records.
Is it possible to be denied an honorable discharge (even if not by way of dishonorable discharge) for treason?
That's the real explosive angle to this, the idea that Kerry was treasonous and that whatever treasonous act he committed is documented somewhere as part of his military record.