A valid point, but it is conceivable that a similar clause would find its way into larger licensing/development agreements. Turn-by-turn could have been some gem thy wanted to hold as Google's one-up on any client built using their own API. Truthfully, it would be dumb of Google to give away everything, and keeping turn-by-turn (or even just a broader navigation scope) is something I can see as the ace in the hole they hold onto regardless.