And a lot of church-goers are just going to do what their pastor tells them, and a lot of "low-information" voters are just going to vote according to the smear e-mails their cousin forwards. The fact that wardens et al. have more substantial power makes the two qualitatively different -- but then again, last time I checked, voting here was done by secret ballot. If the warden (or gang, or whoever) knows how an inmate has voted, something has gone wrong.

Your second point would hold more weight with me if I found the logic of barring prisoners from voting more convincing in the first place.