Depending on the condition of the belt, perhaps a family member can determine if it looks like something Bob owned or not.
I find it very odd skeletal remains are found near Monrovia less than 6 months after we learn of two unnamed poi's, and that those poi's are not family. Wouldn't it be something if the poi's decided dumping Bob's remains in an area familiar to his family might redirect attention back to Bob's daughters and SIL?
According to reports, Bob was wearing shorts when he went missing. However, those reports, iirc, came from Bob's daughters who did not see him the day he disappeared. I don't think JeM would likely recall, down to the detail, what Bob was wearing that morning.