I believe the psychopath text description you quoted may refer to the negative buff given by not burying colonists corpses which I'm sure is different to "observed corpse".
For example, in real life a psychopath may not be bothered by not burying someone because of social standards (it's the right thing to do) but he will probably be bothered by the stench.
For example, in real life a psychopath may not be bothered by not burying someone because of social standards (it's the right thing to do) but he will probably be bothered by the stench.