I didn't listen to the talks-to-psychopaths-guy.
In most situations, most people can talk with a psychopath. Mostly because even those that are floridly psychotic can carry on a discussion. Granted many times the pressured speech and mania make the conversation pretty much one sided.
The important consideration is not to support the delusions, doing so makes those in a delusional state more affirmed in their beliefs and can make recovery more difficult.
On the other hand direct confrontation with delusional beliefs can escalate paranoia and potential violence. And can make the mentally ill person much more resistant to therapy.
It's one thing to engage a person out of concern and a desire to keep another safe, but an entirely different thing to make it about bravado.