Eiruvin 69 - Mechalel Shabbos On A Drabonon

The gemara makes a distinction between one who violates shabbos privately vs. one who violates publicly for the purpose of being able to be mevatel reshus. At first the gemara thinks that shabbos is no different than any other violation where according to R. Meir one who is chashud for one is chashud for all, and according to the Rabbonon one is only chashud for what they are known to violate. However, Rav Ashi concludes that a mumar to violate shabbos publicly is considered a mumar for the entire Torah just as a mumar for avoda zara is. We also see clearly from Rav Yehuda Nesia in our sugya that if one is embarrassed to be mechalel shabbos in the presence of an adam gadol, even though they are mechalel shabbos publicly, they don't have a status of a בפרהסיא מחלל שבת. Rashi explains the sugya on the top of 69a regarding the person who carried into the chatzer on shabbos to be an issue of mumar (unlike tosafos who says that the issue is whether after carrying to the chatzer on that shabbos one can be mevatel reshus). Tosafos d.h. ka'an, points out that according to rashi even a mumar to violate shabbos on a drabonon is considered a mumar. R. Akiva Eiger (Y.D. Shulchan Aruch 2,5) has a long discussion about this issue. Regarding why we consider a mumar to be mechalel shabbos publicly to be a mumar for everything, Rashi explains in Chulin 5a that a mechalel shabbos publicly is kofer in ma'aseh breishis - ה במעשה בראשית"הקב והמחלל שבת כופר במעשיו ומעיד שקר שלא שבת. Based on this we can understand why Rashi would hold that even a d'rabonon violation of shabbos can consider a person a full fledged mumar. It is not the severity that Shabbos has over other issurim that makes it worse, rather it is what Shabbos represents. Therefore, even a d'rabonon violation of Shabbos, when done publicly is essentially making a statement that one is kofer in ma'aseh b'reishis. On the other hand, it would seem that according to Rashi, the concept of shabbos is what makes it different, not the severity. Therefore, one who would me mechalel yom tov or even yom kippur publicly would not assume a status of mumar since their is no association with being kofer in ma'aseh breishis. Had the issue been just one of severity, it would be possible to argue that Yom Kippur and maybe even yom tov are severe enough for this purpose to be like shabbos. But, since the issue is not one of severity, it should only apply to shabbos. There is a teshuva of the Maharam Mi'Rottenberg who says that even yom tov and yom kippur are considered like shabbos for this purpose that one who violates publicly would be considered a mumar for everything. Another point that evolves from Rashi is that Tosafos asks why should a tzidoki and kusi be better than a mumar, they also violate at least the d'rabonons of shabbos even publicly. To which Tosafos answers that although they have a theology of rejecting d'rabonons, practically speaking they keep the d'rabonon so as not to upset the prushim. This implies that the underlying difference between the tzedokim and the prushim was not in their actions, rather in their theology. Therefore, one who doesn't believe in Torah min Hashamayim as the Rambam describes, even if they keep mitzvos meticulously, they would at least be no better than the tzedokim.