Yes, sorry - my mind wandered onto the wrong track

They care that the husband is going to leave when his visa is not valid, but I was thinking along the lines that if he tries to come back after already having spent 6 months in Canada, he would need to prove a valid reason they should let him back in (ie, that his relationship is genuine and he's not just trying to come back to establish PR, spouse or not). From my experiences with CBSA as well as Nexus and the immigration process for my wife's US green card, they do care if you spend more than 6 months of the year in the country of non-residence.