You make excellent points. I was the oldest child, a girl, and I had two younger brothers. My parents and us kids had many conversations when we were little about how one day my brothers would both be bigger and taller than me, but they would never be older than me. We just couldn’t understand that at all.
These parents are doing a serious disservice to their child.
You know how mean middle school girls can be to other girls. What will they do to an imitation girl? And would middle school boys hang out with her? No way!
They are preparing a future suicide case. It would be far better to straighten him out now. He will go through much less trauma learning to like being a boy than he will as a drag tween.