Most people also support political positions that are orthogonal to or even against their self interest. That is what makes them different from corporations.
Literally nobody will benefit from a ban on abortions. That doesn't stop people from taking such a position.
You're using your own personal definition of "political", in which positions taken in rational self interest are not political, but this isn't how it works. It's difficult to have a discussion if you're using your own definitions of words.
It seems what you're really trying to say is that corporations should only act in rational self interest. As has been pointed out, there are circumstances in which a corporation can be acting in rational self interest by supporting abortion, or by taking other politically-charged positions.
The whole rational-vs.-political dichotomy you're trying to put forth is a false one; being political is not synonymous with being irrational or whatever you're suggesting.
Literally nobody will benefit from a ban on abortions. That doesn't stop people from taking such a position.