You're correct in the reproductive issues that cis women face, but why would that make trans women not women? The point of the article was to point out that trans women are still oppressed and their rights should be fought for just as hard as cis women, because despite getting oppressed for some different reasons, they're still just as important in the fight against the patriarchy. I'd include trans men as well, even post-op, because they're just as criticized against by the people oppressing cis and trans women. So, to be clear, the point of the article was to point out that a uterus or birth sex isn't the most important in terms of oppression. Is it something that is a factor politically? Of course, but that doesn't mean sex is the only thing that matters. Gender and identity in general is just as important, even if for different reasons. No one is saying a cis woman's lived experience is the exact same as a trans person, because they are different for obvious reasons.