From the replies to that: "During a launch, anybody can call Elon and abort the launch." [0]. It seems like they want to go in the complete opposite direction of when NASA launched the Challenger despite an engineer telling them it would explode [1].
[0] https://twitter.com/zlsadesign/status/832995766436179969
[1] http://www.npr.org/sections/thetwo-way/2016/01/28/464744781/...