The visa officer might be suspicious that the marriage is jost a marriage of convenience designed to help get the applicant in to Canada. If the sponsor is not going back to Canada, then certainly the only reason for the marriage is to get the spplicant in to the country.
Sometimes the sponsor may have close ties to the country he/she is waiting in, even though a Canadian citizen. The visa officer will expect more proof from this type of sponsor. Basically, the visa officer looks at the situation and makes a judgment call. For example, a Canadian citizen got in to Canada as a sponsored spouse and then became a citizen, but was born and raised in Pakistan. Then she gets divorced. Once she is a citizen, she is free to sponsor her new spouse from Pakistan and to go there to live with her spouse while waiting for his PR visa. But the visa officer may well be suspicious that she doesn't really plan to go back to Canada.
Contrast this with a Canadian citizen who was born and raised in Canada, but who after long delays decides to go and wait in her husband's country for her husband's PR visa. In all likelihood, the visa officer in the first situation is going to require more evidence that the wife is going to reestablish herself in Canada than will the visa officer looking at the second application.