I'm sure they will argue that they are protecting consumers by preventing potentially untrustworthy repair shops from buying authentic replacement parts.

This is what an anti-competitive monopoly looks like. You cannot even choose where to get your laptop repaired, so there is no possibility for anyone else to offer, for example, a cheaper price for the labor. And the consumer pays the forcibly higher price. Those shops that attempted to offer cheaper repairs were retaliated against by Apple...