Definitely, and even worse that that, even people like Colin Caffell and Brett Collins to give a few examples, neither of whom were in any sense "participants" or had anything to gain from Jeremy being convicted are also called liars.
I would not say they are liars. They simply believe a version of events.
It is only relatively recent BC has popped up. He contributed to Theroux's doc and if I recall correctly said he thought it would be JB's style to pay a hitman.
CC has something to gain emotionally. Far easier for him to believe his former brother-in-law is responsible for murdering his young sons than their mother. Assuage his guilt. Not that he is in any way responsible. But to believe its JB means he doesn't have to have the conversation with himself about whether he could/should have done more, seen it coming, not allowed the twins to visit WHF etc, etc.