I am not a doctor and I could be very wrong in my interpretation.
When I read that "the liver is enlarged and mostly replaced with cystic masses most consistent with diffuse hepatic metastatic disease" I understood it to be referring to the possibility of cancer. I believe that "metastatic" suggests that, if there is cancer in his liver, it is not primary liver cancer. That means the cancer stared somewhere else and spread to his liver.
I truly hope I am completely wrong or that, if by chance, I am right then the doctor's findings are wrong.
Good luck,
Mike
It sounds like possibly he has cirrhosis or at least fibrosis in the liver. The ascites usually doesn't 'show' until liver disease is fairly advanced. The first thing he needs to do is find a hepatologist and stop the cause of the liver enlargement/disease (ie alcohol, obesity) if it is that. He can certainly be treated for most of these things.
Good luck!