is that the athlete who did quite well at rio but was apparently really sick leading up to it?

Maybe, but not the only race, whenever he mentions on his social media he isn't well you know he is going to have a blinder.

This is the scary bit. Without medical need, you were prescribed a steroid and an antibiotic. I would class that as doping, though apparently it officially isn't.
If you needed prednisone or antibiotics, I would have no problem with you using them, but "keep me as well as possible" sounds like code for "dope me please Doc".

Antibiotic resistance and destroying your microbiome are real things too. Doctors and 'patients' might want to consider them before taking antibiotics when they don't have severe bacterial infections.

Insulin is a banned substance...I take it everyday (multiple times) to stay alive....I will most likely continue to do so unless directed to stop by the Slowtwitch docs

But I think that in this instance it could have been classified as a doping offense. The USADA document noted in the OP states that the determination of medical appropriateness and necessity is not made by the doctor that the athlete saw, but rather by USADA or their designee. Are they likely to classify this as a doping offense? Surely not as they have been so "generous" with similar cases of elite athletes who should by the letter of their rules have a proactive TUE rather than a retroactive TUE after they have been caught (if I understand WADA code correctly). But I think my point remains that systematic anti-doping efforts have room for improvement in the enforcement realm in cases like this rather than the need for a specific rule change.

I know it must be very hard to live with a chronic disease which has such wide reaching implications as DM. However WADA code does attempt to prevent you from treating your disease and continuing to participate at competitive sport. Therefore WADA (and the doctors on slowtwitch) encourage you to continue a healthy lifestyle in both triathlon and in appropriate disease management.