I don't buy the idea that the home owner should have known it was a paintball gun, even if he wasn't deaf. Stress of the moment, initial reaction of being shot at, etc, it being night, potentially windows breaking, etc. Hell maybe the homeowner was even hit. Paintballs hurt, having never been shot with a real firearm, I'd consider paintball painful enough to confuse for real injury in the heat of the moment.
Paintball gun reports when firing would generally never be mistaken for a gunshot in a low stress environment, but when multiple sensory inputs are telling you "you're being shot at", maybe even already shot, in the heat of the moment??
It's an unfortunate outcome, but the fault lies solely with the holigan, not the homeowner IMO. I can see how I might do the same thing...