i think we can doubt anything in this story.
if i get son's point of view in the right way it would mean that
1/ only clues coming from MJ are "pure" : but MJ cannot speak out loud, he obviously need spokesmen and they MIGHT be his own family.
2/ the family knows nothing and all clues coming from them are purely created by them, going here and there because they have no idea : i will speak my mind on the following words : if they were not in on it, and had ANY idea that there could be a hoax, i think some of the jackson would have taken this opportunity to make money (this is what i think) In the end, they all "more or less" play their part and NOBODY publicly talked about the hoax theory (good or bad) I think if they were not part of it, they would have try to use it for their own purpose and that would have been seen. They all played a part in the hoax, with clues, pictures, interview...
3/outside knowers : i have no idea honestly because at the time he was preparing/finishing the hoax, we cannot "really" say who could be in the know. After the hoax i think many people who knew him came back with their "insider" flag :smiley-vault-misc-150: telling to anyone what they knew about MJ.
4/ Lets put as much fakers as you can image on the net, in the media, all those people seeking for money/fame/attention or just bored by their own life.
I agree you can doubt, but i think on a "general line" the family has been almost normal since everything strange that happened, happened to be stage or containing hoaxies in a very obvious way.