This argument justifies any unethical behavior. "Some bogeyman on the other side of the world is (letting computers decide to kill people | manufacturing and using bioweapons | torturing their captives for information), are you really going to let your 'ethics' get in the way of our safety?"

Maybe you don't think there is any line we shouldn't cross, but I'm guessing you do. The fact that other people draw that ethical line in a different place shouldn't be all that surprising. The people you're addressing likely believe that the US can achieve its defense goals without turning over matters of life and death to LLMs or image recognition systems.