Thanks, Mr Fernie, that does help.
Campbell does not tell anyone what to do, but he does consistently undermine public health messaging. In the early days he was ahead of the curve on matters such as air dispersal / ventilation, but it has been clear for some time that he is now mining a seam of controversy and his success as a YouTuber depends on continuing to dig. He is not respected by mainstream experts, and that is part of his appeal. But if statistics as a school subject was taught effectively, people like him would wither on the fringe where they belong...