What if the plate at the back of the robot takes a heavy hit, bends and locks in? Having a link/retaining cover will lead to more questions about how to build it strong enough and reliable enough to undo 100% of the time.

Lets face it, if someone cant fit a LED to come on when the link is pushed in, then they are going to have serious problems wiring up the rest of the electronics.

I honestly dont see what the problem is with a simple LED. Its a power indicator, not a your robot is safe indicator.