Sure, if you're whistleblowing something systemically unethical - as may well be the case here - then you should be able to do the right thing without fear of negative consequence. I.e., your employer, Amazon in this case, can't fire you.
However, speaking in more general terms, some people just love to whine and complain about things that simply aren't that important: I've worked with plenty (none at the moment, I hasten to add).
For example, and flipping it around: is it a Good Thing for you to trash talk your employer just because you don't happen to like your boss very much? No, I don't think it is, and I think it's entirely reasonable for you to get into trouble if you do.
Is it a Good Thing to trash talk a potential employer because you didn't like their hiring process? No. If other potential employers read what you've said they might choose not to interview you even if your concerns are legitimate. You can stand on principle if you want but of all the issues in the world you could stand on principle about, is this one really worth it? I'd say not but you may disagree.
Getting more serious: what about if your boss is a bully? Should you publicly trash talk them? No! Are you out of your mind?!?? You should do some research and find out how to deal with it effectively and in a way that doesn't damage your future career prospects, either at your current company (which may be a lost cause) or elsewhere, which may include getting and following legal advice.
Certainly for these serious issues: bullying, sexual harassment, discrimination, and so on, if the issues are with a specific individual, rather than a systemic or cultural problem, whistleblowing is probably not the way to go. Note that for certain safety issues, or breaches relating to personally identifiable information, you may have a legal obligation to notify even for isolated incidents, depending on your jurisdiction (IANAL).
The problem with trash-talking your employer, or even former employers, is that you risk sending a signal to potential future employers that you are a troublemaker. In some cases this is not an illegitimate concern, and because of this employers tend to be cautious, which can harm your prospects.
Let me reiterate that I'm talking about trash talking in general, not the specific case of these Amazon employees, and very much not whistleblower activities involving systemic ethical failings by an employer or organisation.
That is not what I mean. This conversation is about the accepted "law of nature" that if you say bad things about your employer you will probably be fired. As you point out, sometimes there are good reasons to publicly say bad things about your employer. Therefore, it is bad that firing is the accepted consequence regardless of the situation, and we should seek to change this status quo.