Scans_Daily

It's probably cannon since in the end the very nature of it is called into question at the end when it's revealed the report was written by Harley Quinn when she interned at Arkham.

The more seasoned of the two Arkham guards who where discussing it then tells the one who found the report to just get rid of it and forget about it. The fact that it was written by a woman who went mad becoming Joker's #1 fangirl. Hence once more offering up that multiple choice option of Joker's origin. That sometimes it could be one way and other times another. It all depends on what deck is dealt in Mista J's mind at the time. God that was the only worth wild part of Countdown, those Villain Origins.