GAW -“If the Chazon Ish knew how to do brain surgery from learning Toirah, Kal V’Choimer the P’nei Yehoshua knew what smoking would do to the lungs from his vast knowledge of Toirah! And still, the P’nei Yehoshua said smoking is healthy. Either “Nishtanu HaTeva” (which I have never seen in an anti-smoking P’sak) , or the studies were not done on Yidden, who react physically differently than Eino Yehudim (as per Chazal).”
You’re ignoring Rav Shlomo Zalman (????? ????, ???? ????? ?”?, ?’ ?”?) quoted above who says that we follow the doctors of our times even when the opinion of the Rambam is otherwise.
Even though the Rambam was talking about Yidden, we don’t say the doctors opinion only applies to goyim.