Piss off the west. I’m sure the major countries that support Russia today would continue to do so. And getting removed from power is something Putin’s been paranoid about forever, hence the doppelgangers and such. I’m sure he has very thoroughly thought out plans to disappear on his own accord if needed.
That being said, using nukes just seem very counter productive to Russia and I would hope even a deranged Putin, or at least other oligarchs, realize that.