Essentially, I accept that there are circumstances in which conventional criminal arrest would be unavailable, in which the conventional rules on search and seizure would not necessarily mitigate the security risk, and in which in which law enforcement may actually have a bona fide reason to want to do something. The law does not provide for any avenue at present for them to do anything. That's the gap in which I think a system of carefully tailored preventive attention might be usefully deployed.
I leave open the question as to whether Bill C-17 is the best way of filling that narrow gap. I've already outlined some of my concerns about the practical implications of using it. I do accept the argument, however, that there is a very narrow, slender gap that right now is not filled by conventional law enforcement tools.