If I were to speculate, it has probably been in the works for months now. G+ changed leadership back in April, and the winds probably changed direction with it.
[1] http://bigstory.ap.org/article/googles-top-social-networking...
[1] http://bigstory.ap.org/article/googles-top-social-networking...
Edited to add: Yonatan also mentions in a comment on the official post that "Vic was 100% involved in the process and approved the whole thing months ago." I can vouch that this is the truth.
edit: I'm being downvoted, but remember that Vic is the one who pushed the names policy in the first place.
So if you still don't think that's enough to believe it, well, that's your prerogative, but I doubt anything is going to convince you in that case.
That said, do you know what evidence made Vic push the names policy in the first place?
No idea on evidence question.
I have a hard time believing that a single person at Google (Vic) would be given so much free reign to make policy changes based on how it "felt" without having a shred of evidence. Unless I'm misunderstanding?
At this point I doubt a name free-for-all is going to swell the occupancy.