I would imagine they were resting him for the game against us.
I did more digging, and it turns out Altidore missed the game last week with a quad strain. He was probably still recovering yesterday. It's ridiculous not to list him as at least questionable but that's always unreliable. I would consider him questionable for us as well, and now think there's nothing fishy going on except the usual gamesmanship with injury status lists.