I'm sorry, I wasn't clear. I meant when he got these people involved in his life to begin with. After his death, they undoubtedly got to see more of what went on under the hood of his life. Chirine's comments kinda suggest that he had given them a certain amount of time to make a statement of their own, and then made his findings public when they didn't.
My point is that they were gaming people who got involved with a game (because of an interest in gaming), inherited the game IP after his death, and then* found out he had some dirtbag beliefs (and failed to be forthcoming for a significant time). We have no reason to believe that they themselves harbored the same beliefs as Barker.
*unless he'd exhibited outward indicators of his beliefs, in which case they might have had suspicions.
Everything I've heard about the Foundation (before this all blew up) is that they are like if your uncle Joe was part of a poker group, and one of the group dies and leaves everyone else an old inactive bauxite mine. They each think 'well there has to be some profit to be had in this thing,' but no one really knows how to achieve that (because one guy in in advertising and the other a barber and so on). So they just kind of sit on the thing, protecting their IP rights but not really producing much with it.