I see this repeated often enough where it is presented like some nefarious plot. While I think it is nominally true, I think a better way to think about it is to think of what HR's incentives and motivations are, and to realize there are many areas where your interests do align with your employer's.

For example, a primary responsibility of HR is "keep the company from getting sued" when it comes to personnel matters. A really shitty HR department will interpret this as "sweep shit under the rug", but a good, competent HR department will handle things above board, according to established procedure. A good HR dept. does this not because they want to be nice, but they realize that the best long-term way to keep the company from being sued is to make sure complaints are handled above board.

In general, when evaluating how people will really act I think it's best to leave morality out of it, and instead realize where their incentives are coming from and try to align your goals with those incentives.

While I agree that's an important possibility that you should mull over, in this case, firing was absolutely the right thing for Apple, for Sculley, and in all likelihood, for Gassée as well.

He said it himself in the article: When the general and his lieutenant disagree too much, the lieutenant must go. Sculley has made the right decision.

There can be only one CEO; if I'm not on board with the mission and direction that CEO wants to take the company, I don't belong there. As level-headed adults, it's time to negotiate the terms of my leaving...

That doesn't seem to be the case here though.