His orgasm allows him to escape without answering.

James is so focused on his sister's questions that he doesn't even feel his impending orgasm coming until it's too late. His warm cum floods Britney's already pregnant pussy, silencing her questions. Britney still isn't used to having her brother's cum flooding inside of her despite everything that has happened. The feeling of her brother's warm thick, 'gross disgusting' cum quickly fills her body and clears her mind. So much so that she doesn't even hear the door to the restroom open and close. By the time Britney collects herself, James has already disappeared, leaving her alone in the bathroom filled with his cum.