The point is, if you make them look stupid to the broader population, people are less likely to come in. It's about recruitment, not mitigation of existing terrorists, at least how I understood it.
Right. So the question to ask, then, is: will the potential shorter-term increase in attacks from trolled terrorists be more or less than the longer-term decrease in attacks due to fewer new terrorists being around?
If it were Americans (or anyone else who worries about being a terrorist target already) doing the trolling, I would seriously worry about that. But if it's local people discouraging each other, I figure the risk is pretty small.
