The FSF wouldn't participate in a lawsuit like this because from the FSFs ideological perspective, the mistake is allowing Apple to have a closed source system to begin with (because they declared victory in the 90s and since then have shifted towards blaming users for not using Free Software); at most you'd see a head-up-ass press release after the lawsuit is settled, because that's what the FSF usually does; probably easier than actually putting in the effort to do anything to advance Free Software politically. The FSFe from what I can read in this post is actually cognizant that Apple actually has a market share and that opening up application development on Apple devices is a major step to ensuring a healthy Free Software ecosystem.
The FSF these days is a decrepit organization whose primary purpose in practice is to enable Richard Stallman to not have to participate in modern society and to host his philosophical screeds. It's issues are so specific to it that in terms of FOSS, they're a historical artifact at most. Even in the US, the SFC does more for the average free software developer (ref. the recent Bambu incident where they stepped up to help a developer from getting legal nastygrams from the company in question.)