I think we can generally agree that there's something of a dilemma when it comes to this kind of thing (not speaking of the claims made in this particular case but in general):
MTF transitioning has the best cosmetic outcome when puberty is blocked. That requires for the process to begin before a certain age. Conversely, that gives the patient less time to decide, "Do I really want to go through with this procedure which is in some respects irreversible?". For that, they ought to have plenty of time. Going through puberty as normal helps them establish their sense of self and gender identity. To force the process without the benefit of this could very well ruin their lives.
As for children below surgical age, the approach towards "gender neutral parenting" would ideally mean simply that both kinds of toys and whatnot are available. A normal boy will gravitate towards masculine toys more, because the girl toys are not as interesting, though it shouldn't be considered unusual if he dallies with the girl toys somewhat. Unfortunately, these results can be skewed depending on whether he has a sibling of a similar age, and what gender that sibling is.
When I was maybe 4 or 5 years old I did a little bit of playing with girl stuff because the only sibling who wanted to spend time with me was the sister immediately closest to me in age, and I followed her lead on most things. I grew out of it, though some nudging was needed.
The approach of explicitly or implicitly nudging towards toys, clothes, and styles of play appropriate for that gender is what gender-neutral parenting seeks to avoid. But then he will surely be nudged by his male peers. Either they will explicitly pressure him to reform, through cruel taunts or more physical means, or refuse to associate with him until he does. There is no guarantee that the girls will want to associate with him, or him with them, since they are not like him. So in most cases truly gender-neutral parenting will result in boys who are boyish overall, as the school of hard knocks will set him straight eventually. It's a level of temporary misery that could've been avoided by raising him as a boy as is normal.
Unfortunately, in practice what most examples of "gender neutral parenting" mean is "enforced equal exposure", rather than equal opportunity of exposure. Explicitly encouraging boys to play with girl toys, which skews the results as he's not likewise praised for playing with the boy toys. Him wanting to receive more praise from his parents, a perverse feedback loop ensues, until finally they've got him anesthetized in an operating room in Thailand with the doctor preparing to chop his 12 year old dong off.
