By contrast, there is no shortage of people willing to work for Google. If the most ethical people with the strongest moral compass leave, then they may be replaced with people who have less aversion to working on military drone contracts, or other things.
Smart people can be moral, they can also be amoral. Google can continue to execute with either. What you're suggesting could lead to a 'morality drain' equivalent to 'brain drain'
Previous internal protests have gotten Google to give up the DOD contract, and may convince them to give up on Dragonfly, without having the loudest voices -- who organize other people in the company -- from all leaving.
Leaving is a last resort protest, and often, if you get that far, you've reached a tipping point and there's no going back. You can bring economic pressure and harm to a company by striking, that's how unions work.
I see you constantly make this 'love it or leave it' suggestion on HN, but this could lead to a worsening of Google's behavior, not an improvement.
I've been in the industry since the early 90s, and have worked for several startups, as well as IBM, Oracle, and Google, and in every case, I've encountered more sexism and sexual harassment behavior elsewhere. Good lord, Oracle would take engineers to strip clubs on business trips. You're asking someone to quit a company which might be persuadable to change its behavior, and join other companies of tech-bros who don't have sexual harassment training, and often don't even have an internal mechanisms to report abuse. To what, walk out and quit again?
Sexual harassment and sexism in the tech industry is wide spread, and worse in many other companies. You can't run from it, you should organize collective action where you are and make them fire you. Quitting is the easy way out for a lot of companies.