Congratulations on the COPR and your crystal ball
Yes, he can land and go back to the US. Canada's rules are very different from the US's in this regard - he can land for immigration but not for customs, medical coverage, etc. If he chooses not to become a resident for customs purposes, your issue is going to be the B4 (if it's not ready yet by the time he lands) since you may have some convincing to do when you go up next time and you don't turn it in at that time. Technically, he only needs to turn it in when he goes with the intention of residing in Canada 12 months but from speaking with CBSA folks (they are very helpful if you call them, btw) they advised us not to postpone turning it in if at all possible to avoid a bunch of questions in the future since it's a gray area ... he may not have intended yet but already had the intention to move and made plans to and the call centre said some agents are very strict with this based on calls they get. Alternatively, you could also do the B4 in your name for jointly owned goods if you are also moving up to Canada after an absence of 1 year and everything is >6 months old (if cars, for example, are jointly titled) with no disadvantage for any items valued less than 10,000 CDN.
