I don't agree with "if I don't perpetrate this harm, someone else will, so it's okay" because that pattern can be used to justify any harm. If I don't perpetrate this harm, and someone else does, the moral culpability rests with them and not me; and that makes all the difference.

I'm saying that doing business with people who oppose abortion isn't the perpetration of harm. We as a society do not economically ostracize people who hold a pro-life position. There is no need for some random software developers of some groupware to be doing that.