Her logic assumes that another company would actually pay her that much. Given how disastrous her tenure has been to Firefox's user base, I'm skeptical that another company would even want her as CEO, let alone pay her this much.
Any replacement CEO is going to be thinking, I'm trying to beat Google, Apple and Microsoft on a tiny budget and if I dont succeed people will blame me personally for it all, complain about me online and claim that no one else should employ me. That's a gamble for anyone coming in who has better options and so attacks on the CEO for being a failure only help to create a moat and increase her bargaining power.
Maybe Brendan Eich can come back? Do a Steve Jobs, take back the project and make it into what it was meant to be, primus inter pares among browsers.
And if we want to get conspiratorial, If she thinks her main job is getting the most money out of the Google deal, then Google would be more than happy to pretend shes doing great in the negotiations and pay 5m extra.
The sooner Mozilla loses its dev culture and talent the more power Google has.