The 'Google Ai ethicist resigns...' headlines wouldn't have been any better unless she was willing to sign a gag clause as a condition of getting her preferred

The 'Google Ai ethicist resigns...' headlines wouldn't have been any better unless she was willing to sign a gag clause as a condition of getting her preferred leaving date (which sounds highly unlikely) and I doubt they had any particular need to pay her to finish anything off or hand over to fellow staff. Ultimately if she felt strongly enough about something to indicate she would leave if they didn't budge and they felt strongly enough about not budging to let her go then the finishing date is moot. Edit: also you put the stuff about 'agreeing a leaving date' instead of 'I will quit' in your ultimatum to make it clear that you're dead serious about leaving and are trying to be reasonable rather than threatening, not because you need next month's paycheque.