For # 5 - they will throw you under the bus just out of fear of losing their jobs. Nowadays that usually equates to losing your home, savings, credit history...
I don’t know why this guy thought he could publicly attack his employer without consequences. If I have issues with my company, they’d be the last to know (as I exited). I assume this guy knew the risks.
Yep. Don't complain about anything, even about issues that you think are innocuous. Even your salary. If you don't like something, and it's bad enough, find another job.
I assume this guy knew the risks.
I don't know. He seemed pretty naive. He learned some hard lessons about work and life.