Why look for an on/off switch in the first place? Isn't it obvious this probably has more value to those looking to profit by mass extermination, than anyone hoping to use it as something to help people stay alive? Investors fund things like this, and lethality increased viruses, and GeoEngineering, and weapons of all kinds, hoping to see returns on their investments, unfortunately.
It is the problem of the practice of investing itself, that we should be seeking to fix.
I believe we have the solution to that, as well as the problems of planetary energy depletion, in Kardashev Money.
All we need to do is demand it, when we lose hope of all other ways out of our own personal experience of individually coming to the end of our "usefulness", in the old system of profit driven extraction.