That may have just been because they want to emphasize a native mobile app rather than HTML5-based mobile experiences, and Google has not yet released their own native maps app for iOS.

Actually, the open letter also recommends Google and Nokia maps, via their websites (because native apps don't exist).

BTW: Am I the only one that thinks it's fishy that Google's claiming (a) they only had 3 months notice of this change and (b) 3 months isn't enough to produce their own iOS maps app? I don't believe either of those claims.