I've never killed a rooster with any liver damage...always seems to be the hens. I've fed roosters 5-6 yrs on layer and never saw any liver disease or any other disease, for that matter. Roosters on free range consume up to 12% calcium in the greens they consume and that doesn't affect them at all, nor does it affect chicks. I've never seen any evidence at all that layer feed affects the health of roosters, no matter the age.
Fatty liver doesn't have grey spots nor hardness to it, but are more yellowed and friable, fall to pieces in your hands when you try to pull them out.
Maybe more likely to be Spotty Liver Disease?
OK so Spotty Liver Disease is sounding more like what it was. The liver was hard, and it did have spots.
Is the cause of that only from campylobacter? Are there other causes? And if it was campylobacter, would the carcass still be communicable? Campylobacter is a nasty illness...