My experience has been that the things bugging me today were always there in a similar form.
Other stories come to mind, like my dad eliminating an allergic reaction to shellfish by means of mental adjustment (I think it was NLP) and nought else.
I'm left wondering whether your son could be talking himself into it, though one must tread carefully around an idea like this.
Sensory issues are real of course, "toughening up" isn't the answer and access to supports like sunglasses and noise cancelling headphones can make an amazing difference.
With the headphones, at work, the difference for me is that between barely / highly functional.
Chade-meng Tan, in one of his books on meditation, talks about a man who came to his course in a wheelchair (due to pain) on the first session, crutches on a later session, and finally just a cane. He reported his pain hadn't changed much, but the way he thought about his pain had been revolutionized.
I recommend:
1) acknowledge and attempt to support his current experience of his sensitivities
2) remember the widely reported cognitive load associated with putting up with sensitivities
3) ensure that he has access to suitable therapy - e.g. my psychologist is highly experienced in ASD and helping people both see the upside and overcome the weaknesses imposed by their traits. I wish the same for your son.
4) similar-wise for peer and family groups
5) check out (for yourself and then him) the books by Chade-meng Tan, available on Audible and dead tree.
I recommend Joy on Demand first, Search Inside Yourself second.
ASD folks report mixed results with meditation. Getting started is hard like starting at the gym is hard, Joy on Demand addresses those issues which is the reason I recommend it first.
I believe there is value in meditation for most on the spectrum - a literal spectrum of benefits to be had in fact, starting with inner peace, equanimity, resilience and emotional intelligence.
I highly recommend taking a closer look at meditation.
Wishing you both all the best.
_________________
"Stress happens. It can be a stimulus for growth. It can plough you under if not offset by rest. I strongly recommend checking out
Peak Performance by Brad Stulberg and Steve Magness,
on Audible."