I'm sure he can transit through AMS. Although, my understanding is he'd have to remain in the international transit area. This specifically excludes entering Schengen for a hotel stay.

[MENTION=681595]swampwiz[/MENTION]: Are you traveling in Sept.? If not, the Mercure transit hotel may be an option which is scheduled to reopen in two weeks or so. Isn't there also the Yotelair? (Personally, I've only stayed at the Mercure. Merely aware there exists a Yotel. But I ain't sure it's suitable for your purposes.)