I don't think he left Utah without permission; the consequences of doing so would have been drilled into him by his attorney. And he was talking about a move to Vegas before the sentencing, so I would imagine the subject came up.
So I think he got the psych eval done, requested permission to move out of state, and got it. His was a first-time, non-violent, misdemeanor offense, and leaving the state would put even more distance between himself and his victim. I don't see any reason why he wouldn't have been cleared to go be Nevada's problem, instead of shitting up Utah.
As for the psych eval, my guess is he really, really didn't like the therapist's conclusions, and that's why he went silent shortly after sentencing and has never mentioned it since.
Russell, being a Narcissist, doesn't think there's anything wrong with him. And he's dumb as fuck on top of that. So he would have gone into the psych eval fully expecting to tell his side of events, and the shrink would tell the court, "Oh yeah, he's 100% totally sane; no problems here."
Instead of sympathizing with Russell and his plights, I think the shrink pegged him for what he is: a Narcissist with a low-normal IQ, and possibly mild autism. That he was court-ordered to complete a psych eval as part of sentencing on electronic harassment charges put NPD on the table, even before he met with a shrink. So finally, instead of the "softer," less-stigmatizing diagnosis of Bipolar, someone had the nuts to say, "Nope; this shit is classic Narcissistic Personality Disorder, complicated by the fact he's kind of a retard."
TBF, we won't ever know what exactly happened, but Russell failing to meet the terms of his sentence and running off to another state just doesn't seem likely to me. There are rules and laws he feels free to break, seemingly heedless of the consequences, but I don't think he would in this case.