Okay here's my thoughts - I'm a noob so take them with a grain of salt and if I'm out to lunch chalk it up as inexperience.
I don't see entrusting sole evil role to someone new; it would be likely they would slip up and bring the game to an early close.
Don't see it being cat. He could be lynched even if people knew he was innocent. Also he defended RB when it would have been easy to jump on the bandwagon. No potential in the sole evil defending innocents.
Some of the more high profile players (Lady G, JM) are to big a risk of getting lynched early to entrust with sole evil.
You really need an experienced player who is well liked and doesn't garner a lot of suspicion.
My spidey sense says RB.
First tingle was when he told G not to trust anyone.
Second tingle was the big deal over PMing.
Couple of other tingles since.
Inciting the sackless to vote. Could be seeing which way the wind is blowing so he could railroad some innocent.
I could be completely wrong on this, as I said I'm new. This is just a gut hunch. I'll remain sackless for now till I get something a little more substantial in my gut.