I'm sure part of the calculation for the team is that Manning and Rony Garcia will end up coming back and covering part of the workload, which added to Skubal, Pineda, Hutch, gives them 5 starters who should have stamina to cover much of the remaining workload (knock on wood). Not counting any contributions that Hill, Brieske, Faedo, or ElRod they get. Or (unlikely) if the other Rod comes back.
Their situation isn't great, but it doesn't warrant wasting a roster spot on Keuchel. TBH, I don't think there's a team in the league that should be desperate enough, he's toast.