The real disaster is that people are cynical enough to believe and continue to popularise this myth.
Most people think of themselves as fundamentally good. Considering someone who has made decisions based on (well-argued) ethical beliefs to be dangerous would contradict their image of self. And if there's one thing people abhor, it's being inconsistent in their believes about themselves. Ergo: nobody not working for Uber or Facebook is going to have a problem with a do-gooder.
If you don't believe me, consider this: Do you believe this guy, Tim Bray, had both the power as well as the mindset to hire someone who had made a similar stand at a previous job?
Or consider the overwhelming majority in this thread seemingly supportive of this action, and registering disagreement with the idea of not hiring such people. Do you believe they all change their opinion if they are ever promoted into management? Would you?
There is also a vast universe of companies that just aren't in a position to generate the sort of ethical controversies Amazon invites, either by being small or by selling innocuous products.
As a cultural phenomenon, this idea is similar to believing that corporations never do anything that isn't in direct pursuit of shareholder value (they frequently do, sometimes even quietly where it doesn't even generate positive PR).
In a certain sense, these are examples of Keynesian Beauty Contests, where everyone considers the girl-next-door type to be pretties, but bets on the blonde playmate with fake breasts to be chosen by the majority.