@prettybird
I am neither a statistician nor a medic nor a dietician nor an academic nor a parent of an autistic child but
at a purely observational level, I would query a correlation between a HFLC diet and autism when the apparent rise in the prevalence of autism predates what is
still essentially a niche diet (even if we find that it works
).
It could be argued that the rise of autism diagnoses correlates very closely with the rise of high carb, high sugar, low fat diets 
But even I know enough science to know that correlation does not equal causation 
Isn't there some real evidence that gluten (amongst other carbs) can have a negative impact on autistic kids? but not that it caused it I seem to recall reading about restricted diets. 
We can measure gene expression very precisely with microarrays or enzyme-linked immunosorbent assay and put it through some data processing. It is a measurement, not a point of view. It is expression levels and differential expression testing. It is empirical data, not an opinion.
Gene expression of 48 genes linked to ASD is altered in maternal High Fat Diet.
In summary, the presented results indicate a key role of maternal HFD during pregnancy and lactation in the disturbance of normal brain development, which may predispose offspring to the development of ASD symptoms. Exposure to a maternal HFD alters the transcription and translation of ASD-related genes mainly in male offspring, and these changes may result from epigenetic modifications (including the degree of CpG island methylation).
For those who want more details, on which genes:
" At PND 28 in the frontal cortex of male offspring from the HFD group, an increase in the expression of, inter alia, genes was observed, including Cttnbp2, Gabbr2, Nf1, Shank1, Syn1, Taok2 (involved in synaptic function [42,43,44,45,46,47]), Ankrd11, Ash1l, Baz2b, Crebbp, Setd1b, Kmt2e (involved in chromatin regulation [48,49,50,51,52,53]), Ankrd11, Btaf1, Med13l, Nf1, Spen, and Taok2 (involved in transcription regulation [49,54,55,56,57,58]). A majority of high-confidence ASD genes, including genes whose proper expression was disturbed in the frontal cortex of male offspring exposed to maternal HFD, are characterized by functional pleiotropy and play a key role in proper brain development and function [8]. The direction and lifetime point when pathways related to genes with pleiotropic functions are dysregulated will lead to different, even opposing, effects, resulting in neural and symptomatic heterogeneity reported in individuals with ASD [8]. "
Full text : www.ncbi.nlm.nih.gov/pmc/articles/PMC8467420/
Gene methylation during pregnancy matters. In most cases, we don't know what causes hypo or hypermethylation. As an example, we know that hypermethylation of RASSF1A causes preeclampsia, but we don't know what causes the alteration of RASSF1A. A 2021 paper has brought light and data on the methylation of 48 genes linked to ASD , identifying the cause of the changes in maternal High Fat diet.
Great. New knowledge. Every time we get new data on the epigenome, we win. Bingo.