As you said, it seems to me to be a move based out of desperation and weakness, not a hand of strength. If you don't stop resisting I'm going to have to use nuclear weapons. So what, you're going to use nuclear weapons on the vary nation you believe is apart of Russia, with people whom you believe are Russian, and that you believe should be brought under the fold of Russia?
I'm naive and ignorant on this outside of the media coverage, twitter feed, and pictures/videos I digest. But I would have to think if he really was wagging the nuclear dog seriously and approached the point of hitting the button, one of his own or many of them would remove him from power at that point.