It appears that Richard and probably the natives/hostiles do not age in the same manner as other humans. That might have put them at odds with Dharma, as I am sure the dharma researchers would have wanted to study them and run experiments on them to determine why they did not age. I think that Ben masterminded the whole purge. He was the insider, he had the access to the poison gas and the masks....not the hostiles. They took their cues from him in order to rid themselves of the enemy. He is a evil manipulative man, and has lied to everyone.......... I think it is about to catch up with him.