They can legally do whatever they want. They've pulled apps before for the same rule. It's part of playing in Apple's ecosystem. As a developer you always take the risk that Apple will decide to wield the ban-hammer, and you basically have no recourse.
Those aren't even remotely analogous. Nobody required Microsoft to sell Netscape. Microsoft got slapped for using its monopoly in Operating Systems to pressure third parties into not signing agreements to ship Netscape on their products.
The fundamental thing that's lacking here is that third-party coercion. The government is never going to force any company to carry and sell products they don't want to carry and sell.
