Yes, it talks about ownership, because the original poster talked about ownership.

Google hosts files, and thus needs to have some semblance of control over what actually is hosted on it, or they become liable for the same content.

Pirated material? Child pornography? etc. It all needs to be scanned and determined if it violates rights/laws and be dealt with.

Google has always done this automatically, because the sheer scale of content they host is overwhelming.

I totally understand the 'own everything' mentality that some hold. That's fair -- then host it yourself, encrypt it, and you can hold the key to your little kingdom. For most people, that isn't a factor.

To get back to the original claim -- they don't claim rights over what you post. It is yours. You just can't host other people's stuff. The definition of that is incredibly broad and largely commercial. 99% of people will never, ever run into the issue. 99% of the remaining 1% will discover it innocently (such as another poster trying to back up office). The remaining will already be versed enough to encrypt their data locally before uploading.