That's the DEFINITION of "constitutional state"/"state of law".
It means the government can't just arbitrary bend the law if it fit's them on a case-by-case basis. If they want change they need to make a new law.
Even if Epic did act out on apple because of Chinese support the US has to handle the case fairly on basis of the facts of Apple abusing there marked power (which they obvious do, through not necessary illegally). Then, after or parallel to this they can decide how to handle the Chinese involvement, but this MUST NOT affect the given suite. That kinda what being a "constitutional state"/"state of law" is about. It's about being able to rely on the law being uphold independent on weather you family (or investors) might be crime lords or foreign powers or whatever.
The strategist in me thinks that Epic Payments is a provocation rather than a product, they've been in touch with state attorney generals about Apple's antitrust situation, and the real goal is to get that lawsuit out, bring the antitrust hammer down on Apple, and maybe get some free PR and marketing from the press cycle.