We've turned down clients for ethical reasons before. It's not that weird. People do it all the time; they just don't make a lot of noise about it. If the Aryan Nation tried to sign up with us, we'd probably tweet a bit about it. But otherwise we'd just declare ourselves incompatible and get on with our lives and let whoever they are get on with theirs.

So, the assessment you need to make is:

a. How important to your company is the bloc of employees with this client conflict?

b. How much of a dealbreaker to that bloc is the conflict?

c. How much of a dealbreaker to your company is the other side of the conflict?

Pro-choice/pro-life isn't my particular red line (I was raised and still sort of consider myself Catholic, though I'm not pro-life --- but there are certainly pro-life organizations I'd refuse to work with). But there are other red lines, and they do come up, and your principles are usually more important than your customer pipeline, and it's usually just not a big deal to say "no" to people.

Ask your lawyer --- not a message board! --- about the legality of refusing to work with pro-life advocacy organizations, but I'd happily bet money that you're just fine on this. The bigger issue is how you want to handle your relationship with your team.

You might come up with a compromise, if you don't want to publicly take a stand that will attract attention that could harm the company (and that is a possibility); you could, for instance, make a countervailing donation (at some multiple of revenue) to NARAL.