That web site references Grabau, who references Bearss, who references two sources, neither of which mention a Whitworth at Raymond.
Parker Hills has asked Bearss what generated the Whitworth claim, and Bearss doesn't remember. Hills either then looked in the VNMP collection, or asked Terry Winschel to look in the VNMP collection, and the file on Bledsoe's Battery had been looted.
Personally, I wouldn't put too much faith in Bearss' version of the Battle of Raymond. There are several major errors. Not that I can blame him, Raymond represents one chapter in an immense three-volume study on Vicksburg.