Not just between 2015 and 2020. He has to meet the residency requirements in any rolling 5 year period so say he became a PR on January 1st 2010 and left Canada on January 1st 2013, he will be able to renew his PR card in 2015 based on having spent more than 2 years in Canada. However, in January 2016, he will be 3 years outside Canada completely and would have to return for two years in order to meet the residency requirements. He might get away with not doing it if he has a valid PR card but for example for someone who is not visa exempt to Canada and is not in Canada and who loses their PR card or it is stolen or destroyed, they would have to apply for a travel document to return and the travel document does not ask did you have a valid PR card or did you meet the residency requirements in your first 5 years, it asks if you meet the residency requirements for the past 5 years.