It’s that they are treating it as something weird. Uhura’s race and sex weren’t treated as weird because why would it be? There wasn’t anything especially special about Geordi being a blind helmsman when TNG premiered, because making accommodations wasn’t anything special - it was normal.

What Discovery did was performative inclusivity, which is a more subtle form of bigotry. It’s pointing at someone and calling them weird and claiming moral superiority for tolerating their presence.