The real problem is that given his rank, he would be in a position to hear things sooner than others further down the food chain. Anyone paying attention to who is doing any betting could have (or should have) asked what they might now that would cause them to place the bet they did. In this case, it boils down to an OPSEC violation, and that's illegal under any circumstance, punishable by UCMJ if not actual civilian law. The fact that the FBI are involved tells me that this guy will probably be facing UCMJ violations too (if he's lucky, court martial if he's not), and may not be a Sergeant Major any longer when the dust settles.