Ummm, the runner touching home before Cincinnati stepped on 2nd and 3rd means nothing. The batter touching first beforehand also means nothing. C'mon man... the plays at 2nd and 3rd are force outs. That's the same as argueing that a runner on 3rd advancing and touching home on a traditional 6-4-3 inning ending DP is safe because he touched home before the defense completed the DP. :S :S
The only part that makes this situation a bit murky for me is the fact that a grounds crew member picks up the ball and throws it in to Brandon Phillips, I'm assuming this makes the play an automatic ground rule double and all runners advance 2 bases. If it wasn't for this, the Reds 100% got stiffed.
Edit: If the Official ruling was that it was a ground rule double, then the final score should reflect that and read 6-4 Diamond Backs. Because the final score is listed as 5-4, I have no idea what MLB's official ruling was. Probably just didn't give enough f***s since it was Arizona vs Cincy.