That wasn't their argument. Their claim was that the web page should not be altered before it is rendered in the browser.
And that's a terrible argument made by clueless people. I'm surprised the court let them get away with wasting their time. No one could or should expect to control exactly how a web page is shown to the end user because you don't know their presentation requirements. I probably need new glasses and turn my browser's font size up to what is probably an absurd degree. If the day comes when I'm totally blind I'll use text-to-speech or some other accessibility tool according to my needs. And I'll stop using Adblock Edge when they pry it from my cold, dead hands.