I think I have the analogy

If you're going to try to murder someone with a gun, the GOP will applaud that murder so long as you DON'T check whether the gun's safety is on or off. Why? Because so long as you DON'T check the safety, you have no way of knowing the status of the gun. The gun could be lethal or it could be benign as can be. And so long as you don't know for sure that it's lethal, you can't be held responsible.

My point?

If you're going to out a CIA agent and risk US national security, just make sure that you don't check in advance whether that agent is undercover. So long as you don't check, you don't know for sure whether outing her will risk the lives of every CIA agents, our soldiers, and every American. Maybe she just sweeps floors at the CIA, who knows? So long as you don't know for sure that she's a covert agent, you can't be held responsible.