Is that generally illegal in the US? if not then what specifically does the retaliation have to in response to to become illegal?
e.g I would expect negative retaliation in response to poor quality work or slacking off etc, and would expect it to be legal. This person's actions would be considered intentional bad PR, so what specifically about retaliating to it is illegal?
(Genuine question)
You cannot be "retaliated against" if you aren't engaging in revelations of illegal behaviour. These people were not doing the latter, when you look at the details. They were merely protesting against things they didn't like, but which aren't illegal, and in one case, didn't exist at all (Google underpaid men, not women).
If there's no illegal behaviour, there's no whistleblowing, and if there's no whistleblowing, then reducing "job opportunity" (which is of course not a right) is just ordinary corporate performance management in response to an employee behaving badly.