1. ...to compromise the idea of openness at all...
The point is not to be open. Openness is a tool that Google uses to create the product and ecosystem that it wants. In sacrificing a little openness, it loses a little bit of the perks of being "open," but probably gains other things, so I can respect that.
2. ...to compromise the idea of openness entirely...
I don't think we can say that they've done this, at least not yet. I'm just look at it as an experimental branch of the code that isn't yet ready to be merged into the trunk. It makes a lot of sense to me that, if they rushed this code out for strategic reasons, that they would want to keep it a little close to the chest until it was more stable. Remember, while to you this is an abstract principle of openness, to them this is a product they ship, and they WILL be judged on its performance.