Wow. Many? There are only two platforms, Android and iOS. Android barely has any competition with Play and iOS has no competition for the App Store. So who are the rivals?
The Play Store and the App Store do not compete as they cater to distinct audiences.
It was a prepared canned response that barely addressed the question, but since each rep only gets 5 minutes to ask questions, Cook (and others) could basically answer however they wanted because there's no time for follow up.
The anti trust laws were designed to prevent exactly this type of action the article is talking about, but we've given big business so much political sway I don't have much faith the laws are enforceable at this point.
The wider they can cast the net, the easier it is to fend off antitrust controls, or at least the threat of them, as far as their stockholders are concerned.
This was all about subscriptions, and the customers weren't watching or had stopped watching on apple devices in 2016/17, so Apple was willing to concede the rev share % to retain subscriptions that started on their platform. Now Apple gets to count those numbers as subs, even if they aren't watching on Apple devices anymore.