I don't have a huge problem with this as long as it is not so tied up with bureaucratic red tape as to effectively act as a stop for refugees entering America for the next several years.
I think everyone takes their risks with allowing refugees in, and has to be willing to accept some of that risk, as it will never really be completely eradicated. Part of accepting some of the responsibility for helping create the refugee crisis is helping solve it, by taking a share of them into your own nation, Canada included. It's not like 1000s of terrorists are going to be slipping into the US this way... Will a few perhaps arrive? Sure... but that's a risk you take with any immigration small scale or large scale, and has happened in the US many times already. It doesn't mean you hermetically seal off your border because 1 in 10,000 or 100,000 refugees might be a terrorist.