That would mean there's no malware on closed stores, which is simply not true. Besides, you can allow more than one store and still have high security. More to the point Apple doesn't care about protecting your rights, but their margins. More stores means lost profit and that's the only thing Apple cares about.
Also, assuming big companies are more capable of doing proper security is just flawed way of thinking. Just look at Sony whose hacking and leaking credit card numbers is approaching annual levels. If anything I'd say some security nut will do a significantly better job than Apple, because no company does something if they really don't have to, especially Apple who will opt to glue piece of shoe rubber to push on GPU chip instead of losing a penny on changing soldering paste. And it's not an isolated case either, on iPhone Max series they removed a single drop of adhesive which made sure chips were strengthened when phone bent slightly. They saved pennies there but that caused user's phones to lose touch on displays.
Just repeating their PR statement doesn't mean that's the correct way to go.