How does defense argue against strict clinical protocol of rare genetic conditions in med-mal?

Much of what I see when looking at cases in oklahoma and reddit discussion has to do with a bad surgery, or tragic stories because of shitty doctors. Rare conditions seem to have, well. Rare amount of cases I suppose. I'll pull from something I'm familiar with only because of how strict the protocol is for my point. Acute Intermittent Porphyria. 1 in 200k

• Intermittent episodes
• Not curable
• Attacks requiring the ER because they are life threatening
• All untreated attacks chance permanent damage or death. Only takes one attack/bad luck.
• Negligence would speedrun patient deterioration/attack escalation, risking their life.
• Most people are asymptomatic. So if an attack presents in a textbook fashion, the "First line of care" is specific *because* it's life threatening.
• This information is drilled into patients by all medical literature, specialists, and AIP foundations. There's also emergency lines for PCP's/ER 24/7.

There's no exception to this protocol. Many common medications can make it worse, so family history secures proper treatment in emergencies regardless of diagnosis (gold standard can only be done IN an attack biochemically) Genetic panels themselves state it cant be used for diagnosis.

If history is disclosed on ER arrival or when establishing care + documentation confirming family hx, or something from a specialist and the textbook severity is clearly presented, how does defense argue something like that? Liability is already pretty high