I don't believe any of that personally, I doubt Gotti himself was in the same room. Gotti was in Florida with his family at the time Favara disappeared anyway.
I think Favara was just shot to death. I think probably Charlie Carnig took care of it, his version of the story should be in the book Mob Killer but I haven't read it. It can't be that accurate anyway 'cause the guy never flipped.