I think it's extremely likely that any system for identifying and exiling psychopaths can be co-opted for evil, by psychopaths. I think rules and norms that act against specific behaviors are a lot more robust, and also are less likely to fail or be co-opted by psychopaths, unless the community is extremely small. This is why in cities we rely on laws against murder, rather than laws against psychopathy. Even psychopaths (usually) respond to incentives.