Now we are officially in a Catch 22 situation. Someone can land then leave Canada and retain their PR but how do they prove that they will staying at ANY Canadian address permanently IF they have a return ticket in their pocket?
1) They don't tell the IO they have a return ticket in their pocket unless the IO asks.
2) If the IO asks and refuses the address given based on the person not being there when the PR will arrive in the mail, get a form you can fax to CIC with a change of address and fax it before leaving Canada.
3) If that doesn't work, apply for a PR travel document at the embassy before going to Canada the next time and during that trip, try for the PR card again.