Um... Isn't this a form of "entrapment"?
Subject says it all, good definition here: http://www.lectlaw.com/def/e024.htm
A point worth considering is the "to commit a crime that he had no previous intent to commit;" to which we should be asking if the feds are passive posters, or leading somebody on in order to get the desired result. Given they are using false personas, who knows what other prompting they may give to achieve the desired aim.
Furthermore, I'm not really sure if a reference to the moronic behaviour of Mrs. Drew is even related to this story. It is like a "here's a worst case scenario we can use for doing something very similar in the name of 'good'", aka "think of the children", but if a 13 year old tops herself because a person she doesn't know says the world would be better without her, well, what can you say? Her life must have been pretty screwed up already. And who's to say a screwed up 17 year old won't be led astray by the feds and nicked for "offences" he may well not have committed on his own initiative.
Furthermore, and just to kick an idea around for the sake of it, if the feds do manage to get an adult male to request a nudey shot of said fake-persona, and they haul his computer off and find nothing because he isn't really into that (but figures his Facebook friend probably is) then *technically* he requested from an adult using a false persona, hence no crime has actually occurred, and secondly one could say asking a not-child for a nude picture is less messed up than posing as said not-child offering a nude picture.
Meh, this one's a can of worms alright. Exclamation mark as a warning for obstacles on the road ahead...
[of course, in reality, there's probably very few pervs that don't already have a disc stuffed with incriminating evidence, and if by chance they find a clean system, a serruptitious prod of a USB key with AutoRun and a couple of batch files will sort that in under a minute... can even be done on-site if the mark is distracted by the big dude with the bigger gun]