Not even people who claim to be “trans people” have been able to come up with a clear, nailed down definition.
Yes. If we were ONLY talking about persons who were 10 years past a complete hormonal and surgical transitioning before they decided to attempt enlisting in the military, it might be possible to formulate a consistent standard for acceptance or rejection. But in practice, the trans community insists that “trans” might include hormones without surgery, or “social transitioning” — cross-dressing and a change of pronouns — without ANY physical changes, by either hormones or surgery.
Furthermore, SOME trans advocates insist that a person who’s already in the military should be able to transition while on the job, thereby dragging all of their colleagues into it. This is obviously different from the case of someone who’d gone through transitioning as a civilian, long before seeking to join the military.