if I as a 38-year-old had a mild liver impairment which could reduce my life expectancy to 60 (22 years from now) I should get priority over a 60-year-old with a debilitating, excruciating condition which will end his life in six months, merely because his life expectancy with the transplant may only be 70

No. Because it's mild and could reduce your life expectancy. Once it becomes worse and a will, yes--you should.