In all fairness, it sounds like the invader was clearly insane, and I imagine the medical examiner is going to find some very interesting brain damage, maybe even a tumor, when he cracks open his skull.
And yes, it probably goes back to the “traumatic brain injury” he had as a teen. Severe migraines after a TBI are a major red flag, especially associated with an indeterminate “mental illness” and severe paranoia.
Bottom line: the people who defended themselves are blameless, the home invader likely had no control over his actions either.
And I would blame his family for letting him out on his own.