My obsession vehicle.

Doctor Who: The Wedding of River Song, Doctor Who: The Time of the Doctor. 

Can someone explain this to me? Please? Dorium said that on Trenzalore no creature can speak falsely or FAIL TO ANSWER. The Doctor is asked his name over and over again for more than 300 years and he never once answers. I don’t get it. I’ve been trying to think of some way this ISN’T a plot hole.