I'm trying to explain (perhaps poorly?) that the change is not simply semantic. No one who is part of Google proper has any say in what nest, glass or those other companies do at this point. None of the culture, support etc... transfers over. The CEOs of these new alphabet companies are free to do as they please. What you're seeing here is this in action.
Saying Google are somehow accountable for nest or glass is like saying that dropbox are accountable for the actions of reddit. They are literally that disconnected now when it comes to how the businesses are managed.