I think raising testosterone can help some with some symptoms, but isn't a cure for me. There are other things that can help raise testosterone that don't have much effect on POIS and can actually make it worse for some (intense exercise, a good nights sleep, both make POIS worse, being sleep deprived actually helps symptoms for me which reduces test levels).
If low testosterone is what causes it, I wonder why testosterone is low in the first place. Doesn't seem like a root cause.
I'm very sure the answer for me lies in the microbiome, I think there's some pathogenic bacteria that is hard to get rid of and has damaged the gut lining causing foreign undigested food particles/proteins entering the blood stream, not sure how it directly leads to POIS. Alot/most of the treatments and cures seem to be related to the gut (antibiotics, antifungals, diet etc) and/or treating an inflammatory response (curcumin, anti-histamines, niacin, etc).