Menachem: Rav Moshe Feinstein and the majority of poskim rule that to be a tinok shenishba a person has to be totally and completely unaware of Judaism. Anyone familiar with frum Jews is not a tinok shenishba.
Regarding saving lives on Shabbos, Kitzur Shulchan Aruch 92:1 “Shabbos is pushed aside for Sakonas Nefoshos… therefore it is a Mitzvah to desecrate Shaboss for a Kosher person (even if he sometimes does sins [[ed: not a habitual sinner]]) who is in mortal danger”. Also see also the uncensored Shulchan Aruch Yoreh Dei’ah 158:1. See Shearim Metzuyanim Bahalacha 92:1; He brings the Pri Megadim who says we do not desecrate Shabbos for one who doesn’t keep Shabbos Litai’ovon (for convenience reasons).