As soon as he accepts it, it becomes his responsibility.
It does put him in a tough situation, but if it were me, a simple one. Don't accept it.
You try and do something like that at AK sausage down here, they would have it thrown away before you could blink. They won't even accept good meat if there is too much particulate matter (leaves, sticks, etc)
As soon as he brings in meat with any sign of spoilage, he is now transfering that spoilage to the other meat that gets processed. So if I am a person who takes great care of my meat, gets it in at a good hour, and then it gets stored next to the jackass who left it rotting on the loading dock, my meat gets plenty screwed also.
So he admittedly took in bad meat, went over the limit of his storage and processing capacity, and had meat which wasn't and in some cases couldn't be catalogued.
I blame him fully for it. If I am a responsible hunter, and trust my meat to him, it is his responsibility to make sure that my meat is protected. Having any tainted meat on premisis, or receiving it without the ability to fully protect it is breaking that trust.