Earlier quoted context omitted.
So what is your expert advice? A manager runs their mouth off publicly, gets fired/made redundant, and gets replaced with a manager who does buy into the company line? What concrete differences in behaviour would you expect to see?
A good manager gets in a fight with their superior(s) if their superior happens to be wrong. A bad manager will avoid conflict with their superior, nod too unrealistic demands and then badmouth the superior with their team. A catastrophic manager will actively push unrealistic plans towards their superior. For me the main difference between a good and a bad manager is that the good manager is interested in delivering…
You've put forward a false dichotomy between punching my manager in the face and nodding along silently to everything I'm told. Frankly, both will get me fired pretty quickly.
Business don't work on managers fighting to the death on every decision we think is right. They work on managers pushing back where we think something isn't correct. If my manager disagrees, it's his job to override me and say "I hear your concerns. Do it anyway." That can happen for many reasons, some good and some bad. At that point, however, my role as a manager is to disagree, accept the decision and do my best. Or look for another job.