I think you better recheck your history. Sure, it may not be all that common, but it happens. Think about Benedict Arnold. He was a general (and a brave, skilled one at that) and he is one of the greatest traitors in our nation's history. You may or may not agree, but I consider Bill Clinton a traitor because of the whole missile tech-for-campaign money affair. If you agree, then unquestionably his rank (Commander-in-Chief) is higher than a rear-admiral. Alger Hiss, though a civilian, attained significant influence in the US state department while being a Soviet Spy.
I suppose it is best to note that I am not saying anything about this guy in particular, just saying that you cannot place your trust in a rank.
Arnold was a good officer at a time when the continental army was desperate for any trained officer. It was also a time of shifting loyalties in the midst of a war that was almost surely lost. I'm surprised there weren't a lot more traitors then.