Actually, I think most toddlers are like this, as they try to order their little world. Seth won't start a meal or even a snack until everything is as he wants it. Knife, fork, spoon, glass of water. Cutlery has to be exactly straight, even if he then dives in and eats with his hands.
He can disappear for long periods of time to water the plants at Sui House. This is a complicated operation. Various types of containers are needed. First they need to be lined up, first in size order, and then moved around for some other reasons unknown to us, perhaps pulling one out so it's in front of the others, or moving the largest one to one side. He works in complete silence and in deep concentration attending to his plants. I can sit next to him and watch the whole thing and I suspect he doesn't even know I'm there.