> Monopoly means whatever the decision of the high court says it means and that is squared with the legislative.

Monopoly has a very specific definition in US law, in fact. https://definitions.uslegal.com/m/monopoly/ The legislature might conceivably change that definition in the future, but that's not relevant to the law as it stands today, which is what we're talking about. Microsoft came much closer to that definition a few decades ago than Apple does now, and they still managed to avoid serious consequences.

> There are no hard and fast rules in litigation or civil law.

There are quite a lot of hard and fast rules to be found in every area of the law. It's kind of a fundamental property of the law.