Her face was protected, and he chose not to hit the side or back of her head. But she had no way of knowing that, which must have been what prompted her to change it up on him and try for the mounted position.
He let her.
At least it seemed so for a fraction of a second. But no sooner did she go for her trapped leg did he release it, to grab at her wrist with the same hand while simultaneously turning his body to bring his other arm over and around her own, in a bit of a chicken wing maneuver. If he caught her there, he would turn back and roll so that his body was at a roughly ninety degree angle to her own as he went for the kimura lock.