Depends how big the clan is. If it's big enough then there can be a lot more internal conflict which might make people more likely to not automatically side with the clan leaders. Also, telling noncombatants who are unlikely to stumble across the information (aka: the very old couple at the end of the street who don't have any living children to participate) is not a good idea. The more people know a secrete the less secure it is. Ninjas should understand operational security which would limit the number of people aware of what's going on.