so autists have low IQ

No, autists have problems with speech and behavior recognition.
Usually autists have a higher IQ than what you would guess by looking at them.
Aspergers (defined as autistic in DSM-5) have some of the highest IQs.

IQ is one of the most analyzed, and most proven areas of psychology.

Only the "everyone is a special snowflake" movement has discarded IQ, because they hate being put into boxes. And only people of around average IQ can get away with this.

Low IQ people need help living.
High IQ people are where ALL the advancement of science happens.

There is no denying this.
The research is pretty close to 1.0 on this.