Personally, I've never been very impressed by the, "He's mentally" excuse. It's fairly consistently trotted out as a defense for ISIS terrorists who go on rampages in Europe. The French authorities have already announced that the driver who rammed his car into a pizzeria killing a little girl is not a terrorist, but suffers from mental illness. It's unknown as of this moment if he's Muslim, but a number of past Muslim terrorists have had a history of mental illness. But the media left is fairly selective in taking that into account.