If your brother has ascites (which I am assuming since they want to do a TIPS) and encephalopathy he is not grade A - he is grade B or C. But more important, for transplant purposes we now use the MELD score (ask his doctor what the MELD score is). The A,B,C score is the Child Pugh Score. I suggest your brother gets a second opinion from a hepatologist at a transplant center.
It sounds like your brother by definition is already a Childs B if he has ascites and likely has varices if the doc is recommending a TIPSS. He needs to be at a transplant center before anything else is done at all. The advocate is correct about MELD score, but this is clearly decompensated cirrhosis and needs to be seen at a center where he can be evaluated for transplant. You are slightly old for live donor, by the way. Good luck to both of you! DTD