As David Allen Green points out today, a lot of the "orders" that Trump published are a wish list rather than confirmed legislation. Some are in effect like UK Statutory Instruments - an existing statute allows the president to change the details by issuing an order. But many are not.
Also, as DAG points out, even when they are things that can potentially be immediately implementable as law, a lot of fallen into the old Trump incompetence of poor wording. So whilst it seems that Trump is much better prepared to take over as President and implement a program today than he was 8 years ago, he hasn't got past the old problem of writing stuff so badly it gets taken apart in court.
I'm not sure where this trans order sits in the hierarchy of effective order, badly written order, or wish list. But it doesn't seem very clever to try and enshrine in law something which neglects to take account of the facts of real life. For even biology does not give us a clear dividing line between male and female. And for those with intersex conditions, assignment at birth may either not happen, or else be moot and potentially mistaken. The cultural trans debate is mostly not about people with intersex conditions, although the subjects are not entirely separate either. But clearly law has to take it into account.