That's all only true if he's not DONE.
He was the #16 TE in week 1.
He played in week 2 and got a goose egg.
He's been out for 2 weeks.
He is NOT a top 5 TE currently, nor is there much chance of him supplanting Gronkowski, Graham, Gonzalez, Witten, Keller, and several of the new upstarts, to END UP in that position.
Particularly not if he is out until week 7.
That's a LOT of ground to cover, in a season where TE is making a big splash.
You spent a lot of draft money on him, or you spent a high (for a TE) pick on him.
Gates is awesome, and I am a fan.
It's not absurd to stash him away.
But if you need depth at a position, I would CERTAINLY consider dropping him.
If we were talking about a younger player, or one who doesn't have a history of this same foot problem, it might be a different thought process.
But it is what it is.