Isaacson wasn't basing his statement off of his technical knowledge of mobile operating systems, he was paraphrasing what Steve Jobs said to him. And the whole point of this most recent squabble is not the validity of the claims that Android ripped-off iOS, but that SJ was doing it for show. Isaacson was simply pointing out that right or wrong, SJ was truly pissed of and that he (SJ) believed that it was a wholesale copy. What you are asking for is for SJ to explain why he believed that he got ripped-off (and I believe that he really thought that), but unless you have a Ouija Board all you're going to get is Isaacson's report of how sincerely upset SJ was.
Isaacson is using the situation to promote his book. Of course he'd claim Steve Jobs said that to him. It doesn't mean he knew whether it was just for show, or genuine.