I really don't see how this move can be criticized from a football standpoint. As a backup, he's one of the best in the league. He's not a developmental prospect but the team already has that in Manuel. They paid him slightly above the market rate for his services IMO, which is probably required to come to Buffalo. You've got to give credit where it's due and this was a good move.
Now, it may not make the slightest bit of difference with respect to the team's record depending on what happens with Manuel, but that's another discussion...