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Ultimately, there are a lot worse things in life than having people send you mean emails and write mean things about you on the Internet. I honestly don't consider it brave to incur that, even though it's true that lots of people will avoid saying things in order to avoid those outcomes.
As for lost opportunities and the like -- who knows? There's no way to know what offer you end up not getting as a result of something you say or write. But I think it's pretty clear that I never worry about any of that....
My new bride is (and some others are) of the opinion that I ought to "watch what I write" (or use a pseudonym) because everyone Googles nowadays when hiring, and being in a consulting practise currently, there might even be potential customers that don't take too kindly to what I write ... about politics (albeit, given my job, some might look askance at some of my opinions on telecomm and wiretaps, etc.).
But I'm of the same mind as you, Glenn. If they don't want to do business with me because of my (I hope principled and supported) positions, that's unfortunate ... for them. And they might just as easily take offence to my (a)religion or skin colour. And there's nothing I should (or could) do about those, and I don't think any rational person would suggest I do so.... So be it.
Cheers,