Good point. If Google did as Gruber suggested, and compete with Blackberry instead of iPhone, they would still end up in the same place (touch screen smartphones), because these are all converging to a consensus view of user experience design. The differences are in quality of execution.
Gruber is drawing an arbitrary distinction here that never really existed. RIM and Microsoft have been in the process of adapting in the very same way: Look at the BlackBerry Storm or Windows Phone 7. Are RIM and MS suddenly changing markets? No, they're just evolving to meet consumer demand, same as Google did.