Well, time to update your priors. There's a lot of good evidence about the impact of different strategies on recidivism rates. Here's a fairly recent comprehensive overview: http://static.nicic.gov/Library/023358.pdf
Ah, downvotes for supplying actual research, gotta love it.
Thanks for the link. I could not find the part where it said that rehabilitative approaches significantly reduce the risk of reoffense, but I'll assume it's in there somewhere. Nonetheless, I don't see anything in the document suggesting that, even with rehabilitative approaches, the risk is low and it is safe for private citizens to engage with ex-cons as they do with non-ex-cons.
Ah, downvotes for supplying actual research, gotta love it.