[jandrese]

I'm not sure it would be a good idea for Facebook to produce fake child porn in order to try to provide deniability to moderators.

The moderators are sadly enough going to become experts on this stuff in a hurry, it's not likely that you'll be able to fool them anyway.

[antepodius]

Besides, the people hired to produce fictional child porn would just end up suing facebook for the mental damage incurred to them, same as the current case.