The WISC-V does not weight the WM and PS scores as heavily in the FSIQ as the WISC-IV did, which lessens the disparity between FSIQ and GAI. Also, in your DS's case, his WMI is strong both visually and auditorally, so the WM and PS subtests in the FSIQ kind of offset each other.
I am more struck by the 27 pt difference VCI > FRI, considering how well he did on math reasoning. I suspect he does better when tasks are contextualized than when they are abstract/in isolation--which might explain why the word problems were a better bet than the isolated computations. This is not unusual in conjunction with an ASD diagnosis.
If you could clarify which reading and writing subtests were which, it might be easier to comment on that portion of the testing. (Not everyone reports them in the same order.)
