1. As the first comment on his blog is saying. The first image is a pretty bad representation of Apple's design.

2. When you use box-shaddow (or dropshaddow), then it's not flat design anymore.

I feel like Matthew just wants to coin his "Almost Flat Design" term when there is no need. Design has always been in the middle, except when it was extensively making use of boxshaddow or making everything flat. Then we give it names.

He has a point though, Windows with metro and mobile is doing Flat Design like nobody ever dared and as much as it's beautiful to see, it's a pain to see for a UI designer. Too bad he doesn't write more about this.