Leaving aside the obvious governmental influence in this “private company’s decision”, we, as a democratic society, have the right to decide when and if the two major smartphone OS makers have the right to ban apps. We even have the right to decide whether those exclusive app stores should exist. Whatever I thought about this matter before, my feelings are different after this decision.
Corporations are creations of a democratic society. A corporate charter is granted. As such, it can and does come with strings attached, which can include rules such as "you are not allowed to do this", so long as rules and their conditions are uniformly applied.