"Interchangeable code" wasn't the standard. In fact "interchangeable code" doesn't appear anywhere in the article. What would have invalidated Apple's patent was if the implementation in their patent was "sufficiently similar" to the prior art's implementation. They found that it wasn't, so the patent wasn't invalidated.

I posted the full answer not for your benefit, but for other HN readers. You cherry-picked one part of his answer that gives the impression that the only thing the jury did to determine if the patent is valid is to see if the code would run on other devices. It isn't, as is clear from the rest of his answer.

I'm not sure how you think this jury "made stuff up" because from his other answers, they seem to have had a much better understanding of the law and the facts than followers of this case have had.