Iirc, there is no prohibition on scout more than 2 years apart sharing tents. I think it says "assigning... should be avoided". If scouts choose to share a tent, that isnt being assigned, nor is it absolutely prohibited anyway.
I've never found any place in BSA literature where adults are to assign buddies, tent-mates or patrol membership. I've seen it done many times in various troops, but I've seen a lot of problems with it over time as well.