Also, as far as I knew, while HRod can play 3B, he is still seen more as a 2B.
Considering Phillips may no longer be a Red in 2012, I see no reason to move HRod to 3B full-time. If the Reds do extend Phillips and he is now "blocked," there is still the likelihood that Francisco will be in the bigs and 3B will be open for HRod.
Since Rolen hasn't done too much since the first half of 2010, I think the Reds need to generate as many viable alternatives as possible relating to candidates for 3B in 2013. Therefore, the Reds should challenge Vidal in AA.
I don't think pushing Vidal is going to take away from Francisco and/or HRod. Francisco will likely get his audition this year in the bigs on Rolen's off days. HRod will be getting regular ABs in AAA, either at 3B or 2B and Vidal should be facing stiff competition to give him a chance to play in the bigs in 2013.