Sure, but a lead after 5-6 innings isn't worth much of anything with this bullpen sans Antone. If you think the Reds can contend for a playoff spot this year and your goal is winning baseball games, Antone's a lot more valuable being able to potentially lock down up to 3-4 games a week. That way they can control which games he can influence the most.
It would obviously take time to stretch him out and you're not going to get the same pitcher that you do coming out of the bullpen. We have no idea how he'd translate as a SP. You can't "throw the piss out of the ball" when you're starting a game.