Could a rabbi tell you to make peace with the Romans? Do you have to listen?
Sam, I don’t think it is this letter that is on the table right now. We all know that these types of letters are not authored by the Rabbonim themselves. It is written by whoever, and is not meant to be studied. It is put in front of Rabbonim to sign and they sign when they agree with the point of it. Yes, it is a problem and I wish this system would be uprooted.
Personally, I don’t care about this letter. None of these Rabbonim are my Morei Derech so it does not pertain to me. If they were, I’d try to find out what exactly they hold. However, the discussion here is about the Chiyuv to follow Rabbonim. Your own, the big ones, whatever.
We see in the Gemara many examples of Takanos and Gezeiros that come from reasons of Sakana. They are Halacha, no different from the Shvusim of Shabbos.
Besides, every Halachic decision essentially comes down to judging a situation. Is it Boneh or is it not. We wouldn’t disregard Reb Shlomo Zalman Aurbach’s decisions of Hilchos Shabbos, which are his way of sizing up objects and their functions, so how can we disregard decisions of Shmad, Limud Hatorah, Chilul Hashem, Avoda Zara, Bizui Hatorah, and other Halachos?