Just an anecdote, which I know is not the singular form of 'data', but still: I respect Mozilla as a company, but have no desire to work there (despite there being a lot of technology fit) because the CTO, Brendan Eich, made a donation of $1,000 to support Prop 8—a 2008 California ballot measure which banned gay marriage. Sure, I understood that his views were not those of his employer. But that doesn't make it easie…
Let's pretend I agree with Prop 8 (I don't, with the exception of what ChuckMcM mentioned below). Clearly you feel strongly about it, enough to avoid a company on the sole basis there is a leader there who disagrees with you, someone you may or may not work directly for or with on a daily basis. If I were a hard-line conservative and I knew that about you, I would be terrified to work for you. I have no idea what you might if you come across a blog post, a random tweet, or something else after we've been working together. Surely if you're willing to write off an entire company due to a single $1,000 donation (the line of reasoning goes..), you might be willing to fire me over a mundane tweet about a controversial issue you feel strongly about. This is to say nothing of the huge nebulous area about if I apply for a job working directly for you and we both know we are at polar political extremes.
Ideally, there would be a clear demarcation between public/professional lives and personal lives. I don't care what my coworkers believe in, vote for, or donate to. I hope the same respect is afforded to me.