Interesting views here...
Good for Tim, first off. If you have a conscience and it no longer jives with what happens at your job and it's bugging you, you have two choices: change your conscience or change your job. He's chosen the latter.
I've heard of (and read about) horror stories at Amazon, and also of exceptionally positive experiences. Whether that's a (in)compatibility with the internal culture (bro culture/dick culture/whatever) is another question. Those working in warehouses take the jobs because they need them, not necessarily because that's what they enjoy (but again, we can't paint everyone with the same broad brush), and there will always be an element of human society that takes pleasure in being cruel to others (see the Stanford Prison Experiment if you want to know more) whilst claiming to only be doing their job, and it wouldn't surprise me if that's what is broadly happening in those environments. As for good experiences, compared to some other jobs out in the world, corporate/engineering jobs can be fun and challenging, and you can to a degree ignore what's happening around you or elsewhere in the business. But even in engineering you'll find complete asshats and nice people, and in some instances, the former can make your life hell despite you enjoying what you do.
You'll find this anywhere. It's just that Amazon is one of those places that are huge, touch many people's lives, and hence end up in the press. Google has similar issues, Microsoft has similar issues, software engineering companies and hardware engineering companies have similar issues.
It is good when someone relatively senior (like a VP, although 'vice' anything and 'president' anything is liberally sprinkled across the world of software in the US) stands up and says "Enough is enough, I'm done with this" and walks out. Will Amazon listen? Your guess is as good as mine... I'd venture to guess his job is being filled as we speak by promoting someone. Things go on as before.
Those arguing that political activism doesn't belong at work are right to a degree. Social activism on the other hand should be there, especially when your employer has a vast influence over a vast number of consumers across the planet. That's what defines social and corporate responsibility.