Well I can understand Palmer's attitude towards Halsey. If she does fully know what Halsey did during the war, then all the more reason to dislike her.
Palmer is a career soldier who's conditioned, for the lack of a better word, to respect the chain of command. So Halsey represents the opposite of everything she stands for - disregarding authority, compromising operational integrity et al, regardless of her good intentions and what Forerunner loot she brought back from her little Onyx excursion which, by then, the war had already ended. Not to mention taking a bunch of Spartans with her when they were most needed for the war effort.
I think it may help develop Palmer's character if it was revealed that she lost a lot of men during the war because she was promised Spartan backup and they didn't come cos Halsey took them.
