How is it disingenuous? Are you expecting Microsoft to just give the entirety of their cut to Apple? Stacking 30% cuts on top of 30% cuts does quickly make things "impossible"
They're both assholes in the size of their cut; don't pick Microsoft's side just because they spoke out first.
Apple could argue that it's Microsoft's 30% cut that makes it impossible for developers to get their games published on the App Store. That too, would be disingenuous.
But Microsoft are making a PR maneuver that they can bring to the table to strike a deal with apple.