It probably doesn't matter given we're not trying to legitimize the action. Every mass shooter has a reason without a justification, and some reasons are easier to comprehend than others.
I'm a little more concerned with what Buddy pointed out and this being an easy issue for racists to link to their beliefs about violence and minorities. If it's somewhat easier to comprehend that a man acted on severe pain, it becomes less easy to push the narrative of a black man acting out of base instincts.