Yeah, there is virtually zero chance Houston de-commits to WI.
I don't follow California HS football enough to know if he is really good or not, I assume he is, he's rated high and went to a good football school. I have a good friend who has seen him play a couple times, and he said he's good. The difference in caliber of competition between Nelson and Houston makes it almost impossible to compare the two kids (stats---Nelson by a mile, caliber of competition -- Houston by a mile).
The question with Houston is his team runs the veer. Unless Don Morton comes back, he will have to learn an entirely new offense. He was something like 39-1 as a starter, but as you stated, the stats are not there because they very rarely threw the ball. The program he played at is one of the most successful programs in the country, let alone CA.
He performed very well when throwing at the Elite 11 camps, but how that translates is really anyone's guess. He certainly has all the intangibles going for him.
Will be fun to watch him develop.