I think the broad point is valid though: Apple's platform control is no more morally justified than Microsoft's. And at least in the abstract they deserve equal scorn. But the specifics here are that Windows 8 on ARM won't run an app that can clearly be shipped (and will be for x86). That's a problem with a reasonable hope of being fixed, so it makes practical sense for Mozilla to whine about that first.
Post-post-lastly: it bears mentioning that if Safari was as bad as IE, Apple might draw more fire. It helps a lot to have a browser that doesn't lag the state of the art.