How can you be transparent about your plans if everything is leaked? The court of public opinion tends to not be reasonable and often things that people would get upset about can be corrected via internal discussions.
Otherwise the discussion is private and/or not transparent. (Or at least not intended to be transparent.) Private discussions are usually not be transparent, otherwise the public court will judge.
If Google wants to discuss sensitive issues at an "all hands meeting" then it better be prepared for leaks, otherwise they should stick to smoke filled rooms.
> then it better be prepared for leaks
Leaking something that was brought up questioned and resolved in a negative way is one thing. In contrast this was just live tweeting everything said.
Bringing up complicated topics and having an honest discussion is hard when the whole of the internet is your judge.