In many cases the solution being proposed is basically the same as the problem in the first place. Young people turning to Jihad are doing so in part because they already feel disconnected from society. Emphasising that disconnect further not only means that those who made a mistake are excluded from society, but also means that the attitude of "us and them" prevails... and so more young people will end up joining the Jihadist movements.
No doubt some of these people will never be disillusioned really. Those who are need sympathy and help, and perhaps even will help provide support for those who might want to follow in their footsteps. Another young sometime jihadist who's been there, done that could provide far more powerful testimony not to join up than anyone else.
But even if that weren't true, we still should try to rehabilitate those who are disillusioned.