The perils of having a kid exposed too early to the grand stage. Frankly they should take Harimoto out for sometime and let him concentrate on 2024 instead.
I think it's not so much a problem of him being exposed to the grand stage early. So much as expectations either the JNT place on him or he/his father places on himself.
The problem is the looming 2020 Tokyo Olympics. TH excels, maybe is even the best in the world, at certain aspects of the game, but the rest of his game is full of holes. For his long term developement, he should be working on making his game more complete and filling those holes.
But... with the Tokyo so close, it seems like they are understandably weary of overhauling his entire game (which is what he needs).
Purely on his own terms, 2020 is probably not a good time for him to be trying to tie down a medal (maybe even looking at gold). There's just too much of his game that needs fixing. But after 2020, when the timing would be better for TH, the Olympics are almost certainly not going to be in Japan again in his career. So he's stuck between a rock and a hard place.