Well, I didn't find a real, good definition of 'fetishizing' but, if we agree on the one I'll provide below, you should be able to answer for yourself in this and future cases.^1

Fetishization is the choice to extremely, positively overweight one or more intrinsic qualities of a person or group of people, such that there is a sexual or romantic preference of a person or group of people based on that innate trait, irrespective of their overall character as a person.

Autism is weird for this definition because, while it is an inherent facet of a person, it does have a large effect on how a person grows up. This obviously shapes their character.

As an experiment, take your hypothetical dream person. A second party is a necessity for mental grounding. If you can find another person to assist, have them swap out character traits (social, personal, mental, etc.) until you find a point you'd no longer find the hypothetical dream person appealing.

Anyway, hope you can do some self-study and find that answer.

^1 If you don't agree, then we're piss outta luck and I'm gonna leave.