"If a person is "willing" to be used to allow terrorists commit murder with impunity, they make terrorists of themselves."

I am afraid that is precisely the argument that has been used to justify attacks aimed at civilian targets in all kinds of conflicts, including most relevantly here, Israeli civilians in buses or cafés. "Since you do not oppose the actions of your government, you are legitimate targets".

In the final analyses this seeks to justify any and every action by parties in a conflict. It amounts to a licence for war criminals.