> Why is Nintendo obliged to provide older content, or otherwise allow emulation?
Provide older content, no, "allow" emulation, yes. It's not even "allow", Nintendo doesn't have the authority to allow or disallow anyone from making, distributing and running emulators.
They might not have the legal authority, but is their firm stance against emulators morally questionable? I may agree their methods are questionable, but I don't know if their stance is. Nintendo's stance against emulation seems consistent with their approach to game design and game management.
Is the question of whether a company's action is "morally questionable" dependant on that action being consistent with similar actions done by the same company in the past?