What makes you think they would be able to stop Al Qaeda from entering their country or crossing the border? I don't think they could. The Canadians couldn't (it was US agents who caught the bomb guy).
There just seems to be a much more Jihad sympathetic population in Canada.
I have a lot more faith in the Canadian CSIS (the equivalent of our FBI counterterrorist agents) to stop terrorist plots before they happen than anyone stopping anything in Mexico. You simply don't hear about Stephen Harper's staff selling info to drug dealers or terrorists. But
a senior Fox aide did just that. I do know that the CSIS isn't going to be helping terrorists do anything. I can't say that about the Mexican authorities - they are too corrupt too often. We simply disagree.