Briefly and according to a profile in Current Biography, "since 1962 (Geo. C.
Scott) has asked that his name be kept out of the Oscar competition, the
politics of which he regards as professionally 'demeaning.' Disregarding his
request, the Academy of Motion Picture Arts and Sciences awarded an Oscar to
Scott for his portrayal of Gen. Geo. S. Patton Jr. in April 1971, but the
actor refused to accept it."  And further on: "A dedicated professional who
hates show business and is interested in a good performance, a satisfied
audience, and the judgment of posterity, Scott has no desire to be a superstar
whose acting is indistinguishable from his own personality."
Hope that helps.  Newspaper articles on Scott around the time of the Oscars
that year would probably go into more details from the horse's mouth, so to
Jeff Clark