This is a mystery that needs to be solved! I cannot think of any other dead BB who has ongoing websites, content, IG uploads, etc. years after he passed on. 
I would not rule out “family” or certain local gym friends, or a combination thereof. I do not think this guy particularly kept secrets from the straight world he lived in, but just like the families who don’t report a death to the Pension Board and just keep the automatic deposits rolling in, why not stay on the gravy train? And in Brad’s case, the ongoing gravy train is completely legal.