Except Google didn't offer it to the public. It is an unpublished API that is and was unsupported for external use.
I don't see the problem here.
Actually, they did offer it to the public. This was an undocumented API. However, like the undocumented maps API, it was exposed to the public. As such, it was offered, just not documented.
Don't rely on undocumented APIs
Google actually encourages people to experiment with their public but undocumented APIs as part of their strategy. However, however experimenting with and releasing a product based on it are two different things. Google has a tendency to throw things against the wall and see what sticks. Maps, definitely stuck and they could even monetize it. Likely, this API also stuck, or it wouldn't be news. However, it probably was being used in ways that they couldn't monetize. Which, is why double-speeak of trying to protect the integrity of what it was originally designed for (aka Google Search).
Of course, it is their API and nobody was charged anything to use it, so Google is free to do as they wish with it.