Again, I agree with the premise of your observation; namely, that it's a very slippery slope to start attaching motivation and intent to people's actions. All of us here, I think, can contemplate a whole range of scenarios where someone legitimately has to go and set up a home abroad, whether it's to care for an aged, ill family member, for work consideration or study, or any number of other things.
I don't think that the intent of that clause is to constrain to that degree the movement or decisions of individuals about where they're going to live.
I think you focused in on the true motivation over here when you made reference to passports of convenience or citizenship of convenience. I can think of a couple of specific scenarios in which that applies and where I think it isn't inappropriate for us to challenge the intent of a person with respect to their commitment to Canada.