I have had a hard time convincing my son that halacha does not come about because a Rabbi declares it so – proof from from text, mesorah, and reasoning are required, not simply the personal authority and say-so of anyone. This issue came up with regard to various “piskei halacha” regarding boycotts, both of a local store in the 5T as well as the El Al issue. When someone tells me that the “gedolim paskened” that one should not fly El Al because the airline had flights on Shabbos, I don’t think it is out of line to ask what source in halacha is there which dictates that one must avoid patronizing a company which desecrates Shabbos? Can one buy goods made in an Israeli factory open on Shabbos? Can one shop in a store which is open on Shabbos and owned by a Jew, or go to a doctor or lawyer who is not shomer Shabbos? I don’t know of any source that would prohibit any of these actions, unless it falls under mesa’yeia y’dei ovrei aveira, but that seems a bit of a stretch as in all of these cases your business has no direct connection with the act of chilul Shabbos. Yes, there is a mitzvah of tochacha that demands we speak out against transgressors and encourage them to change their ways, but that mitzvah has many detailed conditions not the least of which is a consideration of whether the person will listen, and certainly tochacha does not in and of itself obligate a boycott.
I guess this press release from Agudah partially answers my question,. Apparently the feeling is that supporting El Al is a chilul Hashem and therefore there is no heter even b’makom hefsed. By extension, there should be no heter to fly El Al even for cases of pikuach nefesh either, but that is not made explicit. I'm simply reporting this as is and offering no personal comment other than to ask that if anyone has seen a written tshuvah that I am unaware of from any of those who signed onto the boycott explaining the halachic parameters involved, please get me a copy and I will update this post as needed.