1) If you think your diplomats are in danger because the host regime cannot or will not guarantee their safety. Probably true in this case.
2) You don't want the other country's diplomats in your country because of activities they are engaging in. Probably true in this case.
3) The other country is engaging in gross human rights abuses and/or has committed crimes against your citizens. True in this case.
4) You have reason to believe that your allies might engage in hostilities against the host nation soon. Probably true in this case.
So, there are several reasons to break off relations. Canada has had recent diplomatic problems with several mid east governments, notably:
1) Gaddafi's Libyan regime. PM Harper went so far as to refuse the dictator's request for landing and refueling privileges when he departed New York for Europe. The RCAF later participated in the Libyan operation.
2) Dubai, which tried to blackmail Canada in exchange for "allowing" the Canadian armed forces to continue to operate a logistics base for the Afghan operation. Canada closed the base and told them to go f*ck themselves.
3) The Canadian embassy in Iran was closed before, in 1980, to facilitate the repatriation of 6 American diplomats under Canadian protection. I think the Iranians are still smarting about that one, but we know who are friends are.
4) Canada was involved in Afghanistan for 10 years and took 158 fatalities. I don't think the taliban, AQ, or their allies like us much.
Even a small power doesn't have to be pushed around by thug regimes if you don't need their oil.
And that Ladies and Gentlemen is why the Sauds have bought and owned our "Representatives" for the past 50 years!
You’re absolutely right... you guys, along with the Aussies, are always with us, you Canadian cousins of ours.