There is only an upside with Spencer, or nothing at all.
He ddin't play last year as we all know, and most likely will start the season on PUP.
So this gives the other players time to learn and get experience. And as things usually goes. Someone will get injured mid way through the season, even if for a few games.
By this time spencer if fully recovered, can come in the last half of the season, fresh legs, and contribute. Probably not take over starting, but can get into the rotation.
If he can't come back, it's not like he was a loss on the DL anyway. But if he can get even 15 to 20 snaps a game, then that is a plus.