The diet stuff... honestly, nutrition "science" is full of contradictions. Sure, too much of anything is probably bad for you, but I don't think diet concerns should be a blocker for receiving a transplant.
At any rate, sorry you and your family has to go through this, and best wishes for your uncle's recovery.
Smoking is the big no-no because it is fairly well proven to impair healing and increases chances of failure.
Evidence against red meat is very weak, and contradictory. Some studies show no harmful effects from non-processed red meat at all. In fact, there is just as much evidence against plant-based diets (they just aren't discussed widely due to the prevailing politics around CO2 etc), basically it's all just noise. Light alcohol use is absolutely fine in almost every case, and John Hopkins routinely does liver transplants for dependent alcoholics with an alcohol-related liver disease.
You should look up some centenarians cases, some lived on a diet of nothing but beer, waffles and blood sausages daily for several decades, and then had a nice healthy liver on autopsy at 100+ y.o., could've been from someone in their 20s.
Such is life.
I'm also in agreement that cessation of alcohol and smoking are much more reasonable requirements for placement on the list than other dietary patterns that are highly individual regarding effects on overall health.
Also, I have no idea if matters or not but he is wealthy (low eight digits) as well.