Seems like a lot to give up for a guy that mulitple bad teams passed on, who can't throw strikes.
As for Blewitt, let's say they bring someone in. That guy gets cut when Stewart comes back....then two weeks later someone is hurt. Do you not promote Blewitt again because you might lose him later? At what point do you just promote him, if he's one of the 9 best RP on the roster? At some point, you either want him up, or you don't. But there will always be someone hurt, not doing well, ready to be DFA/traded/whatever. At some point, a hurt player will come back....