No, shouldn't have to, Ummmm, and at least if they are out of the country they are not plotting mayhem here. That's one way of looking at it. The other is to try to starve Isil of Westernised recruits who will not only breed more but try to indocrinate their friends in the West.
Preventing radicalisation in the first place is the answer, of course, but we have let things slide far too far due to complacency and ultra-tolerance of alien cultures at the expense of our own. There's rather a mountain to climb ahead of us and civil liberties for anyone displaying ostentatious Islamic leanings (e.g. Burkha, Hijab etc.) may have to be infringed. So be it. The first duty of a government is to protect its people.
I don't get much time right now to keep an eye on AB, so apologies if I do not get back for ages.