Can you provide a link to the article?
There has been an argument that sometimes a person's rage that caused them to cause an act of violent was justifiable in the minds of some people or at least draw sympathy. For example, if a father finds a child molester anally raping his 3 year old daughter, and he kills the guy with a shotgun during the act, a mental health expert could use that to reduce the defendant's punishment during the sentencing phase though it'd likely wouldn't allow one to use it as an NGRI defense.
Only reason why I say "likely" is because I've seen judges, lawyers, and expert witnesses sometimes not use the law the way it's supposed to be used. I know, for example, a rapist in a psychiatric long-term hospital that is not dangerous due to mental illness and therefore, per the law, needs to be discharged, and if he commits another dangerous act, needs to be put in prison, but the judge just keeps him in the hospital despite the hospital's efforts to get this addressed appropriately.