In order to remain a PR, the person has to live in Canada for 2 out of every 5 years. And there's nothing to say you have to stay in Canada after landing. In fact, as a PR you're free to leave the country whenever you want, so it's no problem if you leave the day after landing.
The only practical issue is the PR card - when landing, you have to give an address in Canada where they will mail the PR card. If you don't have a place of your own, you can have it mailed to relatives and then they mail it to you. You might need it to return to Canada - people from visa exempt countries usually don't need it, at least not for going through the border, but airlines sometimes want to see it just to make sure they won't have to bring you back if you're refused entry.