That is EXACTLY the purpose of the language.
"The point of not inherently assuming pregnant people are women is to avoid misgendering trans men who happen to be pregnant and calling them women"
We don't need to modify the terminology for 99.99999% of a group to address the needs of the remaining 0.00001%.
Then why are they getting pregnant and having children? At least for the time they are pregnant and giving I will consider them to be women.
Because human being often desire to reproduce.
"At least for the time they are pregnant and giving I will consider them to be women."
Regardless of what you consider, trans men consider themselves men. Their circumstances and medical needs aren't the same since they typically take testosterone and look like average men.
Another reason I don't think your wording works is that the majority consider the concepts of "man" and "woman" to be permanent things.
I honestly don't understand why I have to care about that anymore than if they thought they were wolves.
Most numbers I have seen are more like 0.1%