"Trademark dilution happens glacially over time though, so it's difficult to pin down instances where it's 'obviously ok' for a trademark to be used outside its allowable use."

Nonsense. When I wrote of "trademark dilution", I was referring to misrepresentation on the part of a competitor to gain undue market share, not the entry of that trademark into common usage.

The point (which Google's lawyers are ignoring) is that these are two entirely different things. Even though you and I can "xerox" documents on a Canon "xerox machine", it remains a potentially illegal violation of trademark law for Canon to sell that machine as a "Canon Xerox Machine".

Social dialogue is free. Commercial dialogue (i.e. dialogue intended to make a buck) is not; it is subject to tradmark laws (and many other laws).