When Juan Tomás is talking to kino about the two pearl buyers that were never heard from again, what is he trying to warn kino about? What do you think happened to those pearl buyers?

Juan Thomas is warning Kino not to step out of bounds. He explains that people who try to go against greater powers and against the social status-quo end up in trouble or dead. He says Kino should not test the social order of things by insisting on a fair price for his Pearl. These old Pearl buyers probably took the pearls and ran away.