> How do you defend a company with 30% marketshare being a monopoly but the other company with 70% market share isn't?

One allows you to install different browsers, the other does not.

Being a monopoly isn't illegal (in the US). It's what they do that matters.

Now, that doesn't mean Apple is a monopoly with iOS, because the Sherman act doens't dictate it only looks at US only markets. It look at what makes sense in the context. Of course, a court could decide that regardless of what the numbers are internationall, what matters in this case is just the US market.

Trying to predict that is useless at the moment though because the US courts are all over the place.