You do realize that a person will also be denied a liver transplant if they're an active alcoholic? Are you as outraged about that fact, given that it's harder to recover from alcoholism, as it also has a physical component in addition to the psychological one? This does seem to fit your definition of "ANY group".

The cold hard truth is that organs are in limited supply. These kind of preconditions are unfortunately typical, if statistics show that the recipients are unlikely to survive for any meaningful length of time. I'm sure that the doctors would also want kidneys growing on trees, but that's not how the world works. And yes, that willing donor is still a potential one for some other person.

Speaking of which, there's the flipside of the human aspect. What about the living donors (applicable both for renal and liver transplants BTW)? Is it ethical to perform a procedure that will potentially severely reduce their quality of life for no apparent benefit?

So no, still not the same thing as the Holocaust.

PS. I'm not able to read the WaPo article, since it's behind a paywall. If there's any context that's in the article that's missing from your post, feel free to supply it.
PPS. Congrats, of all the people, you're the one that made me delurk after a couple of years :p.