But there's also not consumer choice now. If devs are so lazy as to only test on Safari because they absolutely have to, you can bet your bottom dollar they aren't testing Firefox or anything else if it comes along. Therefore, if Apple keeps the Safari monopoly on their platform, you have only the choice of Safari on iOS, and only the choice of Chrome everywhere else. So there's no consumer choice even if you get your preferred outcome here.

Diversity is not an intrinsic good. It only is good inasmuch as it enables other things which are good. If the browser diversity we have (limited though it is) isn't actually providing choice to consumers, I don't see how it provides any value even if we do preserve it.