I think the problem is in its asymmetric use. Here they are defining the "market" in question as a subset of the actual market for smartphones or software, restricted to only that software in the Apple store. Surprise, Apple dominates their own store. As if customers don't have alternatives, when of course they do.

If you swap the logic around it would be like calling Apple a monopoly because they are the only seller of iphones, a contrived market that is actually just a subset of the smartphone market.