@lanodan tbh, completely privileged processes should probably die. There should be as few processes with full capabilities as possible. That is not the state currently, IIRC many services still run under full root even when they do not need to change users, access network, …
If only a few processes got e.g. cap_setuid, it would be far more easy to check their behaviour.
(And yes, since capabilities are Linux-specific, this would be complicated)