Seth B,
I too am facing a similar situation. I self-surrender in a couple weeks. From what i understand, as long as he is placed in a designated sex offender prison, he will be much safer. I hear that up to 60% of the population at some of these prisons are men charged with a sex offense, mostly CP. Hopefully the judge made a recommendation for one of these, though it’s ultimately decided by BOP. I hope this helps. Best wishes.
http://www.prisonlawblog.com/sex-offenders-in-the-federal-bureau-of-prisons/