If the sponsor is already living in Canada, then it's not an issue. Of course they don't need to present at the landing.
Problems can happen when the sponsor is living abroad while sponsoring. In order to be able to sponsor, they have to prove they intend to relocate to Canada when the applicant becomes a PR, which would suggest they either have to go with the applicant to land or go to Canada before them.
I don't think I've read anywhere that the sponsor actually has to be in Canada when the landing is done. And I've never heard of anyone being unable to land because their sponsor remained abroad. By that, I think you should be fine with your sponsor staying abroad - this assumption is based on the lack of evidence to the contrary, not evidence that directly supports it, so it's your risk to take.
I checked the operating manual for landing (http://www.cic.gc.ca/english/resources/manuals/enf/enf04-eng.pdf see section 12), but there's nothing in there about sponsors living abroad, so... don't know.