It does seem highly convoluted and improbable (Imo) but I like your post nonetheless! One question that arose for me when reading - I always figured the hospital would be able to confirm scientifically (not just from the victims' statements) what they actually ate in, say, the hours before their hospital admissions. But have just realised haven't really thought through how that might occur.
As I understand it, they all checked in sometime on 30th July after having had symptoms for some hours (maybe they checked in after daylight on 30th, maybe some checked in in the pre-dawn hours - I don't think that's been clarified). If diarrhea was one of those symptoms, I'm now wondering how their stomach contents could be confirmed if perhaps the mushrooms themselves had already been digested or even vomited up at home first. I know at autopsies stomach contents can be ascertained, but by the time the three deceased were autopsied the stomach contents from their July 29th meal would be long gone I'm guessing. Moo
But, and apologies if I'm misunderstanding, I think you're saying that samples of their faeces if taken by the hospital would reveal the stomach contents or otherwise demonstrate the type of mushrooms consumed? I'm not at all knowledgable about that as a procedure, but makes sense and seems logical if the tests can identify some specific particle or whatnot that can be traced back to mushroom type. Also vomit might be analysed for food consumed in last 24 hours or something? Wonder how long mushrooms take to digest? I've probably missed posts about that here - will google it. Moo
ETA: re-reading your post I'm also seeing that you mention that examination of digestive tracts at autopsy could reveal which mushrooms were consumed.