Expanding on this, now that I see others appear to agree with Apple's initial stance, I think the prominent Apple vs. developer examples have been based around an impression that Apple is exercising its power in an effort to secure a competitive advantage, be that through their commissions or restrictions.
In this case Apple's actions would have no adverse impact on the functionality or availability of the app provided the developer complied with their request to rename it.
It does seem sensible that Apple has some sort of editorial control over the content of their store, even in the absence of competitive stores. In fact we implicitly have an expectation of Apple to editorialise - we'd be shocked if illegal or indecent content appeared in the App Store overnight.
As such I cannot see the intrinsic issue with Apple requiring a developer to change an app's name where it is not to provide a competitive advantage.
The developer's framing of the issue in terms of freedom of expression seems weak in this context. It's a closed, private platform, and one where limits on freedom of expression beyond those in law have been commonplace and expected since its inception.