If he's on the forty, and he's out of options, he can't be sent down unless he is DFA'd or on injury rehab, as I understand.
I highly doubt the Reds will start Redmond in the rotation. He has no major league experience starting and this doesn't make sense to me on a contender.
More likely he will join (or replace?) Simon as a longer reliever, who can back up as a starter. Maybe Lecure gets promoted to set up man.
Reds now have a bunch of righty MLB relievers on the forty. Arredondo, Hoover, Lecure, Masset, Ondrusek, Redmond, Simon. Assuming two lefties, two righties will have to go.