It seems like there would be a massive attacker bias in multiple ways. Defenders need consent, attacker does not. Defenders have to work with the human body, attackers only have to break it. Defenders have to stick to the law, which may prevent them from releasing anything at all, attackers do not. And so on. I would not surprised if the attacker's task is a hundred times easier here.
Yep, you'd want to put it on a timer. Optimally trigger it off some natural event, maybe temperature, so it can achieve universal penetration before activating.
