I don't think Fred agreed with you that Naz > Bubu, so I'll trust Fred. In fact, just about 10 days ago, Fred said on KXNO that Bubu would probably start and that he was our best backcourt defender and ball handler.
Secondly, IF he did bring this guy in, he may have told him that if he doesn't pan out his scholarship is temporary. Given this young man's situation, that may have been attractive to him. He didn't exactly have a lot of options. This way, he provides an extra big body for practice, or God forbid injuries, etc. Plus, maybe there is a 1 in 5 chance that he's better than previously thought and earns a scholarship. If not, Fred helps him land at a program he's more likely to contribute to in the spring.