[burkaman]

I'm not sure about that. People who actually want to assassinate the president are not criminal geniuses, or even rational people at all. They're often mentally ill, or at least stupid enough to think that killing the president is a good idea and they can get away with it.

More than one mass murderer has talked publicly about what they're planning online. And two guys that planned to assassinate Obama in 2008 were caught because they bragged to a friend about what they were doing: http://en.wikipedia.org/wiki/Barack_Obama_assassination_plot...

Obviously you won't catch everybody, but I don't think the idea of getting tipped off about a potential assassination plan based on posts online is totally far fetched.