I'm all for them taking action to find people involved in this kind of content, but there are a few points I'd like to mention here. Points which suggest that this really isn't a well thought-out idea.
A few years ago I tried reporting links purportedly to this kind of content. The response was that I had to report the actual page with actual infringing images shown on it (i.e. that I would have to go back, click the links, view any illegal images there and then report them). How could that possibly be reconciled with this latest behaviour?
Dangerous Point Two
Precaching! As most of us know, users of certain browsers and browser accelerators will be sending out 'hits' to links found on a site without the user ever clicking them, just for the purpose of pre-loading in case it is needed. So, we just need to visit a site with these prison-baited links on and it could trigger the authorities to knock on our door.
Dangerous point three
If a police officer puts cash on a park bench and then hides waiting to see if someone takes it, they've not found a theif, they've made one. That is entrapment and at least on the right hand side of the pond it immediately sinks the prosecution.
Dangerous point four
Even amongst technically skilled webmasters there is a high incidence of accidental clicks on links [google.com]. I know I frequently click things I don't intend to click just as a means to set focus - you know what I mean - some annoying popup or dialog box has taken the focus from your browser window so you click the webpage to get it back.
Dangerous point five
There exist many groups both in the US and overseas who are so disgusted at this kind of content that they actively seek it and report it under controlled conditions. Sounds like these new practices are going to make those who are trying to help the FBI the very targets of the FBI.
Dangerous Point Six
Spidering behaviour takes place both deliberately (seo research, marketing), for search facilities (brand protection, niche search), and in covertly (spyware, virus). Typically all these applications are likely to hit pages and then hit all the links on those pages with no human review of each URL before it is downloaded. I can't see any provision in the methodology to avoid the FBI arriving at the door of these people.
In summary, I suggest that this is such an unreliable and tainted means of entrapment that it is akin to searching people because of their style of dress or ethnic background.