I've been thinking about why BG's conviction for false imprisonment and assault is glossed over - except here, obviously!
Maybe it's because it was attributed to his serious drug dependence at the time, which he overcame and has been, to the best of my knowledge, clean and sober every since - and in fairness, well done to him for doing that.
I get the impression that the assault has been 'tidied away' as part of the the period of drug-fuelled excess that BG has put behind him, and that's why it is not mentioned much. That was the broken BG who did those awful things, this is the clean and sober BG who regrets it.
I'm not saying I agree with this, I'm just saying that I think the 'redemption' aspect of BG's life post drugs is why he isn't constantly confronted with what he did in the past.
It doesn't make him any less obnoxious!