I thought he had his citizenship, but 2-3 weeks visit won't hurt anything rather than 2-3 months =NO.
In such cases person has to keep proof of JOB, LEAVE of absence, return PAID ticket, other proofs of property in Canada like rent slips, car loans, pay stubs, insurance etcwhich binds him to MUST go back and live in Canada permanently.
Another guy said:-
"We have also seen a number of spousal sponsorship applications be refused specifically because the sponsor was a PR and left Canada for several months. The rules around this are extremely clear. Since you are a PR, you must be residing in Canada to sponsor. Up to you whether you take the risk or not."
"It's completely at discretion of the visa officer reviewing the PR app. If they feel you've been outside Canada long enough that you're no longer "residing" here, they can and will cancel the application. They won't care what any random call centre agents told you. "
How long you risk leaving Canada for is up to you. Personally I would limit any trips to less than a month, but really it's your decision.