Yeah, I'm trying to think of a reason for a corrupt military official NOT to sell some of the nuclear fuel, or any other part. I cannot think of one. He's not likely to get caught, and if he is, well that means Russia fired their nukes, and so the fact that he's caught is not even the biggest of his worries.
More worrisome is the risk of a corrupt Russian official selling nukes (or parts thereof) to some other organization.