The marker looks too recent and I suspect the marker with wrong death date has been placed years later. The VA lists a phone number for Lobb Cemetery, which may be a source to determine when it was placed and at whose request:

15. RIDER, GEORGE W
PVT CONFEDERATE STATES ARMY
DATE OF BIRTH: 05/16/1807
DATE OF DEATH: 12/26/1880
BURIED AT:
LOBB CEMETERY
LOBB CEM RD BLUE SPRINGS, MO 64013
(816) 630-6581