If the 1000 people did it in coordinated manner with the intent of causing harm to the one person then it would seem like a crime to me. Of course, it's the leaders who should get the severe punishments, but you still have to punish the others too (to a lesser extent). Otherwise you're just saying that it's acceptable to help people commit a crime.

And why are people complaining about the FBI going after people anyway? It's their job to catch (probable) criminals, so they can't really start deciding which ones to pursue. It's the judges and jurys (and lawmakers) who make that decision.