Way back in 1972,the Brotherhood, just as did the Sicilian Mob, deny the existence of their respective groups. One difference was that as long as the Sicilian families married other families of Sicilian background there did not seem to be a problem. Once they started marrying outside their Sicilian groups, such as Genovese, Calabrese, things started to change. Members started telling the deep secrets of the mob.
This is not to say after awhile, even Sicilians got into the act.
The early members of the Mexican Mafia also stood their ground. Even when our first "turn-around," Carlos "Pie Face" Ortega told us about the inter-workings, the other members denied the existence. Those members knew, or felt that anyone who violated the eMe trust would be eliminated and their secrets would remain intact. When "Pie Face" testified against a fellow Mexican Mafia member, Gilbert Pedro "Shotgtun" Sanchez, there were several other members that said "Pie Face" did not know what he was talking about. "Pie Face" had been voted into the eMe some 6 years earlier. "Shotgun" was found not guilty and alot of people did not believe that such an organization such as the Mexican Mafia existed.
Another member, was Mike "Slim" Mulhern. After his arrest with the late Frank "Chivo" Buelna, Mike adamently refuted claims that such an organization existed. He also would later give it up. He testified against a high ranking member of the Hell's Angels. Then there was Michael "Acha" Ison. He was a major player from the San Francisco area. In a taped interview with Steve Mallory, he flatly denied the existence of the eMe. Yes, he too gave it up.
There are several other major "shot callers" such as Ramon "Mudo" Mendoza, Rene "Boxer" Enriquez, and others of lesser positions within the eMe that have turn against their fellow members. Some claim born again Christians, others for whatever they could get from the tax payer through the witness protection program, time off their sentence or what have you.
The bottom line is that when one has his back against the wall, and the price is right, most anyone will take what he feels will better fit his need.