I think that a lot of this makes sense from Google's legal perspective, where antitrust litigation is a constant consideration and any internal document mentioning market share or competitors could be used against them.
I'm sure that there is a great deal of discussion about potential anticompetitive issues within Google and with their outside counsel, but in a context where legal privilege protects against disclosure.
One could argue that they position themselves as an accomplished monopoly already, because their internal correspondence pretends competition doesn't even exist, or is of no consequence whatsoever.
Being a monopoly (or to be precise: to be in a dominant position), is not problematic in EU competition law. It is the abuse of said position that is illegal!
I'm sure that there is a great deal of discussion about potential anticompetitive issues within Google and with their outside counsel, but in a context where legal privilege protects against disclosure.