If they are capable of giving consent, they are capable of activating the system themselves.
You’re thinking of a big red push button, but a button can be a pad that you bite down on, or a eye twitch activated electrode, or any number of things.
The important thing is they initiate the process themselves, so that they have the option to withdraw consent as easily as they gave it.
True consent is not immutable.
The mindset of the whole Israeli government is pretty astounding. It’s like they feel entitled to do what they’re doing, and anyone who vaguely hints at “maybe genocide isn’t your strongest play?” is vilified. Israel is always the victim, no matter who or what is being done. It has strong “the left stole the election” vibes