Why is that relevant? That was not the question before the court. However, to prove an illegal duopoly you have to show collusion. IANAL, but I think it is unlikely anyone could show enough collusion between Apple and Google to reach the threshold of an illegal duopoly.
That is not a monopoly, which implies that the market is controlled by only one company. Not two. “Monopoly” is not just something you say when you don’t like a company. Also, a monopoly in itself is not necessarily illegal or problematic. The real issue is a company abusing its market power, which does not require anything like a monopoly.
> You don't have to meet behind closed doors to fix prices, you just set your prices to be exactly equal to your competitor.
Then it is not collusion. It’s just a poorly functioning market, or something that cannot work as a free market (some natural monopolies are like that).