Yes

There are many children that live with their parents as adults. Some are on AISH and can't afford to live on their own, some are otherwise disabled. There are some parents however, that seem to like having that one (1) child around...a lot of families I know have 1 that mom can't let go of, or feels extra-close to, or that child has always been extra-helpful, or maybe because that child no matter what age, needs that extra help and protection. DG was the only son, there's a lot of work to do on that acreage.
Maybe DG's parents are super-nice people that yes, do recognize that DG has some issues, and want to make sure that he has a decent life. He's their son. IMO, given his history, etc., it would be better for the parents if DG would just go away. If they wanted that, I'm sure he wouldn't have been living there. We don't really know anything about DG's parents' health, its very possible that they enjoy having him around home to help out...it looks like he keeps amazing care of the place. We know that DG can live on his own, as he demonstrated for the 7 years he was away in BC, and we also know that obviously his parents managed somehow while he was away and in jail. IMO, DG lived at home because it was a mutually beneficial arrangement.
I'm sorry, I must have missed something about DG's anger issues...is there something documented about that? I wasn't aware that he had an "angry" or "violent" nature in the past. The crimes he has committed in the past don't indicate that to me. It is possible I've missed that discussion.