While my personal opinion regarding skeumorphic design falls very much in line with the author's, I don't think that there is a contradiction in Apple's design philosophy.

The hardware is minimal because its true purpose is to let the software shine. It's a magical box that can become anything, from a calendar to a photobooth to a music studio. Apple's visual design choices in software have always seemed to fall under the skeuomorphic end of things (faux brushed aluminum?) and having a minimal hardware accentuates these flourishes.