True AI, which we’re still not really near, is self modifying code. So any kill switch has to deal with the concept of how you hide from code that is editing itself the code to kill it.
The kill switch is a 1970s concept when computers were hard wired, were the size of large rooms and didn’t talk to each other.
It is embarrassing when current scientists talk about it.
AI (in whatever state it is in) will be on most cell phones in a few years.