We don't even know if it will work in humans yet. They've only done tests on mice so far, but the gist of it is that they identified a particular protein and a gene responsible for its production. The gene therapy causes more of the protein to be produced which resulted in behavioral changes in the mice. How that plays out with humans is an open question.
I have a feeling I know how it is going to play out with western liberals, though (especially right-wing chuds and anti-vaxx groups): "Ebil CCPP spreading autism via vaccination confirmed!!!"
How our whole body grows is a product of the genes ultimately, so the way brain connections form, balances of different proteins, and so on are also governed by our genetic makeup. I agree that it's obviously a much more complex picture than a single gene. However, if modifying a particular gene does increase production of this protein and that improves the way people are feeling then it's a tangible benefit. Ultimately that's the goal here.
Gene therapies for other genetic conditions often do, but then those aren't neurodevelopmental.
I'm kinda fascinated by the question of how something like this would affect me. Like the way a psychedelic experience can teach us lessons we still retain (and want to hold onto), like the way formative experiences leave deep traces in us even when when we grow and change, what features of autism would always 'stay with me' on some level? If things changed perceptually for me, what old habits of mind would I retain? What would I miss most? What would I not miss?
In a lot of ways I think temporary windows into different neurotypes would be much more interesting than purported 'cures'. People don't usually want to undo their own personalities, including mental dimensions like neurotypes. But who wouldn't want to play with that a bit, if they knew it were safe?