I didn't know him and this is all pure guessing, but, his voice is what I think of as gentle-friendly-open-harmless-vegan-caring-mellow-funny-dog-loving-eco-hippy. The cute, easy-going nice guy who works at the health-food-store, BAKING, of all things.
That persona put on to be a girl magnet, hopefully. A safe guy. Has all the cool opinions...and can get great drugs (the good, acceptable kind)...he just has this other side...edgy, violent, vindictive...but,If one doesn't get too far behind the mask, to a very young thing, he's pretty compelling combination of the good bad boy or the bad good boy. Girls AND boys just want to have fun, don't they?
So, what I think, Moxie, is that's his, "trust me" voice, used mostly with those he wants to think him an honest good guy. He thinks he's pretty good at pulling it off. It reassures him that he's ok, too, because he's scary sometimes. Scares himself.
This is ALL speculation, of course. May be total nonsense...But, in my view, he was bracing himself for what he SAID, not self-conscious about his voice. That voice had served him well. The lies, oops, well maybe not so much. He's carrying the reality, the utter horror of what he has done--in his eyes, in his ears, in his nose, in his hands and limbs. His mind is saturated with insane, bloody acts, the sights, sounds, and smells of the vilest things, done in darkness.
I'm amazed at his outward calm, day after day, hearing, watching his sorry life displayed for all to see. Exposed. It all funnels into the click, click of his pen. Sometimes he writes or doodles, sitting there next to those inept goombas. Imitating a rational person, or letting a soothing boredom cover him. But the tension in his hand...constantly closing, unclosing, clicking...working the pen around & around in his fist, while he sits impassive...I wonder each new day if he's going to explode, but he never does.
PS. I think that anti-bullying post was there solely to show others--and himself--that he's a good guy, you know, caring. So the cause du jour, complete with memes, hey, ready made advertisement for his mask.