How do I respond to someone who says he respects the Gedolim for their knowledge but we can’t follow everything they say. Proof? Look at the Gedolim of Europe who said not to flee Europe when the Nazi attack was imminent. There were those who warned of the impending dangers, like Jabotinsky and others. Yes, it was hard to know for sure, but there were those who warned them to leave.
The reason why we follow the instruction of the gedolim is not because they are right or wrong, but because we are commanded to do so by Hashem. As it is written in the torah “Lo tasur m’kol asher yagidu lecha”. There were many decisions during the Holocaust, that were impossible to know beforehand what the correct thing would be to do. To run to the right or the left, to stay of leave. Everything then was full of danger, and those who made it out usually it was with a lot of divine assistance.
As a side point, I once heard a story that happened in Israel in the early years of the state. There was a taxi driver who was driving a religious man, and he was mocking him, “ look you listened to the gedolim, and didn’t leave when Jabotinsky said, but I did. Your relative died but I lived.” The man replied to him, yes, it is true, that my relative died in the holocaust, and didn’t come to Israel, you came and now look at you. You lived longer, but became secular because you listened to Jabotinsky, and soon you will die. When you get to the next world, you and my relative will both be there, my relative died al Kiddush Hashem and lived a life of mitzvos and will get olam haba. You on the other hand lived longer, ate more, but in the next world you in serious trouble!” True, on a temporary level, it would appear that listening to Jabotinsky might have been better, but in the long run, who is the one more fortunate?
This is something you might be able to use to respond to this person.