If he drops a nuke, he instantly becomes the most dangerous man in history, they only guy willing to use a nuke for normal war purposes (for which there are nearly infinite alternative options), and to flex his ego (which has no limit). Now when he threatens a country, they will have to believe him, because he’s done it before.

With that in mind, I would think nearly every nation with a highly organized covert intelligence service would decide that it’s time to remove that threat from the planet.