Facebook gives its 007s license to kill M, its not particularly intelligent AI

Private company, private reasons

It is perfectly reasonable for Facebook to want to keep mum about what it learned and why it is shutting M down. I do think that Facebook did indeed learn quite a lot from the experience and will leverage that in some way in the future.

Probably for yet another privacy-invading functionality that will unfortunately work a lot better than if they hadn't had this trial run.

But Facebook is under no obligation to answer all the questions and go public on anything. For a company dedicated to dragging everyone's life out into the open, Facebook sure knows the importance of keeping its own secrets.