If you try to make yourself safe from everything, you would never come out from under your bed, so while I acknowledge the SAM threat, no, the clippy tie and breakaway lanyard won't help.
As for the plastique, the tie and lanyard might could make a difference there if said explosive were to be used to blow the latch out of the cockpit door.
I do not find it likely that my 50 seat RJ is high on the list as far as terrorist targets are concerned. However something as simple as not providing a pre-installed leash and/or garrotte to someone who means me harm is an easy precaution.
Secondarily, a long time ago I nearly lost a finger when my wedding ring caught on the windshield frame of a boat. The process of shearing the flesh from the bone was underway when the windshield frame broke. By that token, we do work around machinery. Not that I find it likely to happen, but the clippy tie and the lanyard will prevent my head from being drawn into and crushed by a belt loader.
I don't wear a helmet to protect myself from meteors when I'm cutting my grass, but I do wear a seatbelt when I drive and safety glasses when working with power tools.
(pîr) Pronunciation Key 
