Come on guys, the analyst may be from Goldman Sachs but his analysis is based on stats. In his original analysis you'll see he observes that iPads are not shipping in the expected numbers and that the release of Nook and Kindle Fire (the latter getting good reviews for a $199 device) just before Xmas is a real threat to Apple revenue growth. As I understand it, GS have a reasonable investment in Apple and don't want to see their gain eroded by competition.
Does anyone know why the margins on iPads are supposed to be so low? The hardware is not that expensive. Presumably the rest of COGS is the enormous cost of legal battles around the world, advertising and running a direct sales channel. Any of these factors Apple can choose to change to boost margin.