Metaclass __prepare__ methods can inject names into the class namespace that the compiler doesn't know about, so yeah, it unfortunately has to be conservative and use LOAD_NAME in class level code.
But of course, most metaclasses don't. I wonder if there are cases where the compiler can statically figure out that there are no metaclass shenanigans going on, and emit LOAD_GLOBAL anyway. It seems safe at least when the class has no base classes and no metaclass=.
Aye, that particular case is one the symtable pass could at least theoretically identify.
As soon as there is a name to resolve in the class header, though, it's no longer safe for the compiler to make assumptions :(