If I have written a story based on historical parallels, but have introduced literal mythological or fantastical elements, it ceases to became "historical" in terms of cultural norms and values. Anything that is preserved, is preserved by choice (of the author). There can be (and often are) parallels, but if we're assuming that "wights" actually means "wights" (in GoT) and isn't a poor stand-in for the Celts or the Crusades or whatever (and I believe GRRM to be too good a writer to fall into that trope; his worldbuilding seems solid). The conflict itself may be inspired by a historical conflict, but the sides have been completely recreated in-universe (in fantasy).
People complaining that others are enforcing modern morals on a fantasy book fail to realise that this is a modern(ish) book(s) written by an author who makes intentional choices when portraying his characters (and notably, GRRM has more input on HoD than apparently he did with GoT). If it's not a historically-accurate adaptation of a historically-accurate book, claims of presentism fall by the wayside, because everyone external to the writer is projecting their own personal values onto the source material. Not just the folks allegedly engaging in presentism.