Although it would probably be fitting to describe it as a subset. If you look at vision, then it is a spectrum that includes everyone. Even blind people. If you are looking at blindness, then it is a subset of the vision spectrum that only includes people that meet certain other criteria, i.e. below a certain threshold of vision. Same for autism disorder. Every human is on a mentality spectrum, and autism is a subset of that.
Although it would probably be fitting to describe it as a subset. If you look at vision, then it is a spectrum that includes everyone. Even blind people. If you are looking at blindness, then it is a subset of the vision spectrum that only includes people that meet certain other criteria, i.e. below a certain threshold of vision. Same for autism disorder. Every human is on a mentality spectrum, and autism is a subset of that.
This is how I understood the question, too.