What a lovely question.

From twitter:

The less activist question here is:

If people try to get me fired by smearing the company, will you defend me, or fire me?

They'll always say, 'defend', of course. They're trying to hire you, of course they'll tell you they will stand by you.

However, the people involved in the hiring process are very much not the same people dealing with the public image of the company in the media. At some point an executive will have to make a decision based on public perception and at-will work laws, and decide between "you're too much trouble to keep around. It's not personal, it's just business"  and "we stand by the rights of our employees to express personal opinions unrelated to their employer."

Knowing which way a company will jump is next to impossible to know without explicit position statements or evidence that they've dealt with that problem before. Asking this kind of question during the interview process is great for everyone; if they perceive you as potentially problematic, you won't continue to the next stage. Which is alright by you, since if they consider you a potential problem you don't want to work for them in the first place.