now, the people who were nude in the whole trilogy:
Tattaglia, Moe green, Senator Geary, and Frankie Five Angels...

Ok, Moe Green had the towel, though u could see his butt crack a little, maybe its not him... Senator geary was with the hooker when she died... he was wearing a bedsheet, can't be him.
Frankie Five Angels when he killed himself in the tub, but you didn't see a thing.
so my guess would be Tattaglia. In the novel, it said he was nude when he was with that young girl, just before he was shot and killed, so I'm gonna say Phillip Tattaglia.

If I'm right
Q: He didn't want to sit in HIS chair

Take Care
George
Don Crazyman

"Tonight, The Crazyman family settles its accounts. Monkey and Strawboy, those lil amatuer artist f*cks. they've been screwing with us since the beginning. F*ck'em.
Izabela, my ex-g/f, Tracey will pay her a visit, at her home.
Ruben, take a train to Holman, light a candle for professor Nyman."