I am happy to be proved wrong by hard evidence, but I think the thebaine scare is mASSIVELY overstated. When I read (admittedly years ago) from the Tasmanian government website stated that 'Normans' (thebaine high strain which are used to produce oxy and other Bentley compounds) are carefully separated from the high morphine strains, as these special (Norman) strains are considered a trade secret or protected item. The gov website clearly stated that high morphine seeds were sold on for culinary purposes, while thebaine seeds were destroyed.
The fact is that natural opium (and especially if you are consuming tea from pods with all the natural non-alkaloid substances in them) is pretty rough on the guts when compared to semi-synthetic, or synthetic opioids like Oxy, bupe, and others which have been designed for less histamine response and more tolerability. I started with opium sap and pod tea and then went to opioids like oxy, and I was surprised at how much more tolerarable these were. I suspect upset stomach is just natural. It can be mitigated by taking an anti-histamine (diphenhydramine is the gold standard for me, but first gen anti-histamines will work too).
Again, this is my experience and knowledge. I'm happy to be proven wrong and/or updated.