to be honest I doubt people were masking in response to poop shoving, poop shoving is not the worst and presumably the control group just had non-poop
what seems more plausible to me would be ~<<poop helped something, something made life easier, autistic life is less obvious and disruptive to non-autistics when life is easier>>
There was no control group.
> We note that due to the open-label nature of this initial trial, all of the assessments are subject to placebo effect, however the long-term improvements we observed here are promising.
That study measured a drop from 83% to 17% in severe autism, and one behaviour typical of severe autism is slamming one's head into the wall, among other things.
I think it's overly dismissive to summarise a drop in these behaviours as just "less obvious and disruptive to non-autistics". I can't imagine slamming your head into stuff is pleasant regardless of whether you have autism.