Yeah, it's a bit strange that Fireforge decided for Dwarfs at this point.
Their gear reminds me of heavy renaissance armour, the helmets are earlier and in good comparison to the Northmen, they seem to have skirts with perhaps Scottish style tartans, and the command group has some Landsknecht style heads with hats and feathers. It's a distinct milieu, perhaps fitting for an interpretation of Imperial Dwarfs in the Old World setting. They might have thought about T9A as much as their own vague setting.
No Dwarfs in GoT, so no wonder they don't find a comparison there.
-Z