The essay's button is a private vote. A Permissive Action Link is a coded lock on a nuclear weapon, meant to stop use without a code from higher authority.
National Security Action Memorandum 160 (6 June 1962) ordered those locks on nuclear weapons dispersed to NATO commands. That is a named presidential halt for weapons other people might hold. Robert McNamara later said he had also seen to locks on Minuteman, the land-based missiles in the United States, and treated them as essential to stopping an unauthorized launch.
Bruce G. Blair, who sat in a Minuteman capsule in the early-to-mid 1970s, said Strategic Air Command had set the enable panel to eight zeros. His 11 February 2004 Center for Defense Information column, "Keeping Presidents in the Nuclear Dark (Episode #1: The Case of the Missing Permissive Action Links)," is the public claim: the launch checklist told the crew to double-check that no digits other than zero had been dialed into the locking panel. He told McNamara; McNamara's reply, as Blair reports it, was "Who the hell authorized that?"
The Air Force later told the House Armed Services Committee that "a code consisting of eight zeroes has never been used to enable a MM ICBM, as claimed by Dr. Bruce Blair" (Foreign Policy, 21 January 2014). Blair's 1 March 2015 Princeton note answers with the unclassified Minuteman technical manual then in force, T.O. 21M-LGM30F-1-2 (change 34, 13 June 1973): under normal conditions the CODE INSERT thumbwheel switches "will be set at 00000000." The March 1978 checklist is where he finds the first instruction to insert an unlock code from higher authority. Two officers still had to turn two keys. The dispute is not whether anyone could fire a missile alone. It is whether the coded lock that was supposed to be the President's technical halt was, on the panel the crew actually used, a pass-through.
The hardware existed. The public story was that higher authority held the code. The people whose mission failed if the missiles did not fire are the ones Blair says recoded the lock. That is a halt held inside the agent's own model of why it must keep going.
He already says the interesting question is not which color you press but whether you can tell a cooperation game from a cooperation-shaped non-game. I'll take that. PAL is not the red/blue matrix, and eight zeros are not "press blue."
What that still leaves is a halt that can look like a button and still be the operator's game. "Press red" is an argument about one person's payoff. It survives under any distribution of other people's beliefs. It does not name who may stop an agent that is already running.