You don't seem to have a lot of empathy, or understanding of delusional disorders.
A delusion is a non-real thought that you perceive as true. Things like "I am Napoleon" or "The people on the roof across the street are talking about me" or "The CIA is watching me" are examples of delusions.
Schizophrenia is a profound delusional disorder where your entire mind is completely disorganized. Telling reality from the delusions are impossible because they are coming from the same brain hardware.
I very much doubt that someone intelligent enough to write a complete OS from scratch would be terribly abnormal as a person. Unfortunately Terry is sick, and unless he gets better, whole chunks of his mind are going to be simply wrong.
There's no way to tell; that said, someone with a strong delusional disorder will probably have very few thoughts unaffected by the disorder, and if you're adequately empathetic, you can be charitable and give your fellow humans the benefit of the doubt.
If you read through his "rants" section of his website, you will see he's not a racist, he doesn't call black people "niggers", just people he doesn't like.
Sounds like a fundamentalist and racist to me :\