Exactly he is a small cog in the procedure. And then I'm not even sure today that you could get the foot soldiers to follow such an order if all of the in between had been satisfied. So trusting trump or any president with the codes is neither here nor there.
Historically, retaliatory launches prompted from false positives of launches have resulted in operators overriding a retaliatory launch from occurring and I think an order to launch without the threat of incoming missiles would also result in an operator delaying or refusing to launch.
A Nuclear detonation is more likely to occur from a Roque operator than any Established Nuclear power. As you know nobody wins a nuclear war.
Caption this Meme 