They aren't forced to use Apple as a distribution channel, just like Lenovo could also not sell computers on Amazon or at BestBuy and they probably make a higher margin when they sell D2C as well.
It's a cold blooded move by Apple, but I don't think its "nefarious". I'm very much against their rent seeking with the app store though.
Except they aren't forced to sell through Apple, Netflix doesn't allow in app-purchases for this very reason.