His concern is less about global escalation to some nuke++ level of WMD, but more around rogue states or doomsday cults getting access to control systems for as

His concern is less about global escalation to some nuke++ level of WMD, but more around rogue states or doomsday cults getting access to control systems for asteroid deflection defenses. It isn't implausible: technologically sophisticated death cults exist (e.g. Mum Shinrikyo, North Korea, ISIS/Daesh), important stuff gets hacked all the time, and I doubt most on HN would be comfortable saying "well this stuff will be really secure." His proposed method of asteroid deflection is actually based on using nuclear explosions to shift orbits minutely far in advance of impact. Timing makes it pretty useless for war (as you point out), but very effective indeed for creating a precisely scheduled apocalypse and the global collapse and panic that likely precedes it.