"In a message sent to Pichai and others that linked to the letter, Alex Hanna, a senior research scientist on the Ethical AI team, said it was sent on behalf of her team. A source familiar with the team said it includes roughly a dozen members."

man, this is her own team, this isn't some abstract very removed issue , this people she worked with advocating for her.

Yeah but her own team will probably be the most likely to advocate for her.

Go to any university in the US right after a prof is denied tenure. His students will inevitably protest this decision the loudest.

Also, what were they supposed to do after she sent an email to a huge listserv at the company telling all her subordinates that they should not participate in the company's D&I initiatives and should essentially quit working there? You can't pay people to tell your own employees to stop working for you...

maybe her departure affects their promo cycles

That's a strange way of looking at things. The other 199988 employees aren't on her team. If they had circulated their letter widely and then only got 12 signees then we could say only 6 thousandths of a percent supported the letter.

Why would you expect people outside her team to sign? Would you respect their opinions if they did?

Because it would indicate wider support within the company I assume.

Firing someone is not automatically bad if they happen to check particular boxes. It's the other way around: Firing someone because they happen to check particular boxes is an issue.

If someone is actively bad at their job or is sabotaging others in the workplace, it's quite reasonable to demand their resignation regardless of their sex, age, or family situation, even if it's unpleasant.