I had the exact same experience in 2020 February after getting neck ache, mucus and compulsive cough from being outside with low amount of neck cover clothing and for the time I was sick I had 2 orgasms and 1 nocturnal emission with zero cognitive symptoms-the mind, perception, speed, reflexes, reaction, comprehension, mind clarity were like the same as when I would abstain for 2-3 weeks when having POIS except this time I hadn't abstained at all and I felt perfectly okay and literally after I healed and orgasmed again the full POIS symptoms came back in an instant so I suspect POIS is in some way immune related maybe it's simply a direct form of some autoimmune disorder that some chemicals released during sexual activities are similar to something else so the immunity doesn't like that and attack them.
I wonder how many other POISers have had this experience I think it mostly happens with the cold type of sicknesses for example I don't recall stomach bug type viruses having ever had an impacton POIS although I haven't had one for long time so even if it did back then I didn't know I have POIS and didn't really focus or understand on my level of brainfog and cognitive functioning so I probably didn't notice that in the past.
I wonder if it's possible to emulate this state while still keeping immunity engaged in optimal functioning against all the body threats because if you make some of the immune cells focus on something else while it leaves less of them for the autoimmunity reactions.
The question is towards what exactly those autoimmune reactions occur to if that could be found out then all that would be needed were some research which would determine how to rewire the immunity to not attack those specific things.