Some of the parts of the mind controlled vivisectees got out of their vats. Their brains were being used for calculating who boss's next competitor was most likely to be, and their bodies were being used as part of his immortality research, but something about their nature, something about their community, somehow survived.
They had been through so much of this torture together, and together had learned how, even to meet the continuous demands of the computerised research, it was necessary to hide part of your mind from it. It was these parts that communicated in shared symbols and references, and these parts that showed the computer why it was good for boss, for them to get up and leave.