I do wonder if a medical LLM needs to know anything about popstars or films or classic literature. But your particular examples make me wonder how you could train an LLM to talk medically about "blood pressure" without knowing any physics about what pressure is, or any of the other ways the STEM subjects overlap and blend into each other without clear boundaries - chemistry of drugs, math of dose calculations, language of drug and disease naming etymology, etc.

If a patient with high blood pressure asks "will my face look like Dizzy Gillespie?" isn't it better to answer "No, that was air pressure and cheek damage" than to answer "I don't know who that is, call your doctor"?