Well that does make more sense as to why they are not taking the kidney out. When my husband was about to go into surgery to have his brain tumor removed, the doctor warned us that renal tumors are very vascular ( I think this was the term for it) or in other words they tend to be more likely to bleed more. He did have to have a blood transfusion during that surgery but it was more of a precaution.
Did you dr. think if he took some type treatments and the tumor shrunk that they might remove the kidney then?