Sure they are still liable. To minimize their liability, their design had better be pretty damn good (close to safest possible). I would argue that the Apple

Sure they are still liable. To minimize their liability, their design had better be pretty damn good (close to safest possible). I would argue that the Apple design also has to be close to the most reliable possible design, since a high failure rate will will encourage people to buy questionable aftermarket devices. I would also argue that Apple should not try to make a high profit on safety critical devices for the same reason.