Sounds like the guy may have had some personality traits that under these circumstances are not unexpected for him. You guys are a hell of alot nicer then the vast majority of the companies out there to say the least. Usually no one ever gets a heads up notice of a possible layoff at some future point in time if things dont materialize for hte company.

Sounds like he may have wanted to be let go now so he can have 3 months off paid as the holidays are nice to be off of work if its paid. Seems weird that he also would want to get fired unless he had a lead on a new job possibly and wanted a paid vacation until the new job started.

Dont sweat it you did due dilligence. Sounds like he is smart enough to get a new job so sure things will work out for him. Just chalk it up to his personality and move forward.