He later goes on to suggest that perhaps there will be no "traditional" Windows on the tablet, only Metro, which he discusses having the same sorts of backgrounding-and-suspending capability iOS enjoys. From the article:

It’s worth noting that Metro is more than just a new look, and more than just putting touch first. Metro apps have similar restrictions to iOS apps. According to Jensen Harris, for example, Metro apps will get “about five seconds” after they’re no longer on-screen before the system puts them into a suspended state. There’s no file manager. Users no longer quit (or, in Windows parlance, exit) apps explicitly. These tradeoffs sound familiar?

...Did you (and the parent poster) simply read the Gruber article until you could find something to nitpick, then go with it?