sooooooooooooorry, small correction, actually he can be outside Canada for 3 years every 5 years
this is copy paste from the guide...they don't say anything about after how long u can leave Canada....
"
Leaving Canada to settle your affairs after obtaining permanent resident status
Permanent residents may leave and re-enter Canada as often as they wish, to settle their affairs or to travel, as long as, at the time they re-enter Canada, they can prove that they have been physically present in Canada for at least 730 days within the five years preceding the day they re-enter, if they have been permanent residents for five years or more, or that they will be physically present in Canada for at least 730 days within the five years immediately following the day they became permanent residents, if they have been permanent residents for less than five years. Permanent residents outside Canada may also meet the residency obligation if certain conditions apply."