Cedric is a girl. Con cavity does not always mean there male. The anal scutes and tail is the best deciding factor. That size tail is a female. Males tail would be much longer.
Compare with Joe. Joe has a V around his tail. Cedric has more curved scutes either side of his tail. Looking properly, there is a distinct difference between Joe and Cedric.
I think tortadise coukd be right and that would explain Cedric's lack of butting behaviour.
I want an ancient tort like that =P One day! My male is only 10+ years old... The original owner told me she had him for a little over 9 years so who knows....