I don't understand your logic. So you'd rather the folks that want to harm the airlines, etc... not see them, then attempt to do their dastardly deed and see what the FAM can do about it? I'd rather the FAM be seen as what he is and prevent the occurence on the flight. Sort of like a cop running radar looking for speeders, seeing him causes us to slow down.
Nice attempt, but not very sensible as far as I'm concerned.

BTW, welcome to flyertalk, and thank you for encouraging us to be peaceable!