> I escalated through the proper channels and by the book.
He only left after he felt he had exhausted his options of influence (This being my interpretation).
Leaving just as a knee jerk reaction without making effort to change would be bad, to me personally almost worse than remaining. Of course quitting can be in many cases feel easier/more attractive than trying to navigate through the office politics. But if you manage to flip even small corner of Google or whatever to not do evil (as they used to say) that probably has more influence to the wider society than you quitting.
Counterpoint being that you need to recognize if you are making that change or not, and if you are not able to do so then quitting might be the right choice