He should have no problems coming back. And they have no record of when u left.
But to be safe this is what he needs to do. And i can bet anything it works as i have know a lot of them who have been in a similar situation..
Fly to toronto u do not need visa to enter as long as you have your green card He will have to go through inspection which is random and tell them u are visiting toronto and niagara falls for few days...they will ask were u coming from say the truth (white lie) and say u left US a week back and were visiting friends you will be clear to enter canada then...then go to niagara falls and walk the rainbow bridge into US. It's a 5/10 mins walk from canada to US. There are 3 officers on the Rainbow bridge and they do not have any high tech systems. They look at your green card and let you get in through the doors into US.
Once you are in US then next day walk back as there are better places to eat. This time take a taxi from US to Canada. Then get your luggage and come back into US in a different taxi.
I know atleast 8 people who have tried it and this has worked without any issues.
Once settled back in US apply to get a new green card the latest ones by filling in I-90. this will clean up all you records and you will be fine for future air travel out of the country.
Bunnybugs,
To go to Toronto, he would have to get a canadian visa form the canadian consulate in Haiti, and they are pretty tough there. You need proof of employment and sos and so...
He will just take a chance, if it works, it works, if not then O.K.