There's something really interesting happening in their brain here!

They assume they'd get to react. They assume that they are some kind of ghostly observer that exists outside of the world and can just frictionlessly react to events as they happen, because that's been their entire life and how they've always engaged with politics.

In reality, if one nuke goes off they all do. That's what M.A.D. is all about. Asking "how would they react?" is detached from reality.