Nice question, BassMan_720, it's something I've puzzled over too (INTP here!)
AS and INTJ are both just categories that have been created. It's difficult to say if these categories are "correct" in any fundamental way - they just arise from psychologists observing the variation among people, and then attempting to define sets of criteria that will decide who belongs in those categories. It would be nice if there was a clear relationship between these labels and some aspect of the brain that could be measured with instruments, but there usually isn't anything concrete. I guess the only truly scientific aspect of this labelling is the issue of reproducibility, i.e. whether or not 2 clinicians, or 2 different versions of the test would both arrive at the same result (and it seems in reality, this reproducibility is not great). While there's certainly a lot of overlap between AS and INTJ, they've been defined for different purposes. INTJs are generally less gifted socially, but that may or may not be a source of significant problems. AS has specifically been created to define a "disorder" - and I really think the DSM-IV's criterion "The disturbance causes clinically significant impairments in social, occupational, or other important areas of functioning" is very weak, because we can easily imagine a person who is impaired in these ways, but who might fit very comfortably in a different environment e.g. the academic world.