The measures that people want (and probably will) be implemented will become more Draconian as long as the perception is there that not enough is being done as the attacks inevitably rise. Complaining about Prevent or complaining about foreign policy isn't winning friends or influencing people. The only way to win is to report these people even if it means family members or friends. There's no other solution.
You were advocating detaining indefinitely without charge, not reporting people. Think you're confusing what i replied to there.