Nedarim 32a - Sakana prior to Matan Torah

The maharsha raises a question how was moshe allowed to miss the mitzvah of milah out of concern that it would be dangerous for the child, since the heter to forgo a mitzvah due to pikuach nefesh was introduced with "v'chai bahem" at matan torah? The maharsha explains that actually it is a sevara that one does not have to give up their life for mitzvos (perhaps the sevara is based on r' shimon ben minasya in yoma "better to violate one shabbos so that you can keep many shabbasos", meaning it is better to violate a mitzvah now so that there will ultimately be a net gain in the performance of mitzvos). However, when the Torah was given and introduced the idea that for rotzeach and na'arah ha'miurasa one must give up their life, we needed a heter of "v'chai bahem" so that we don't learn all mitzvos from those. Based on this approach, the heter of v'chai bahem is applicable to b'nei noach as well, meaning that they are not required to give up their lives to keep the 7 mitzvos (but if they would violate without an o'nes they receive capital punishment). R' Akiva Eiger (Y.D. 62) quotes the Pri Megadim (in his sefer on chumash "teivas gomeh") who discusses whether a jew is allowed to give eiver min ha'chai to a goy when he needs it for pikuach nefesh - if he is allowed to eat it for pikuach nefesh it is not lifnei iver for a jew to give it to him, but if he is not allowed to eat it, it would be lifnei iver for a jew to pass it to him.

This is also connected to Rashi in Pesachim 53b that chananya mishael v'azraya were willing to give up their lives and didnt' rely on the drasha of v'chai bahem, because they learned a kal v'chomer from the frogs. The maharsha asks, how can they learn a kal v'chomer from frogs, the frogs were not commanded in v'chai bahem therefore they were allowed to give their lives for kiddush hashem, but chananya mishael v'azraya who were commanded in v'chai bahem, even though they were also commanded in kiddush hashem, should not give their lives. Now, if the maharsha by us is correct that there is a sevara even w/o v'chai bahem not to give up your life for a mitzvah, then the distinction of v'chai bahem should not make any difference since all v'chai bahem does is return you to the same status that you would be without a limud from rotziach and na'arah (which obviously the frogs don't have).