“There is nothing transphobic when a family for their own good identifies the gender of a baby with their predisposition to carry a child or not.”
I’m not quite clear on what you mean here by “for their own good,” but what you are describing here, (i.e. a system by which paramount importance is placed on the role an offspring might presumably play in reproduction) is an agricultural worldview. It’s farming.
People do all sorts of things that don’t involve breeding more people. Right now it’s hard to say with any certainty whether children being born currently will even have an earth to live on when they grow up, much less whether or not a given child will opt to reproduce.
In the midst of everything that’s going on in this wild world, people are literally blowing themselves up to show others their excitement over what kind of sex they think their children might one day be capable of having. I’m not mocking this. It’s a self-own so thorough that I honestly think mocking it would be redundant.