Well, if he wanted to end the fight he could just say so. She'd been confused of his intentions since the spar had been different from just a kenjutsu demonstration. If he needed to get her down and pinned, though, he'd first have to get her back out of the trees again.

Which probably wouldn't be all that difficult, in fairness. It would be an unusual Chuunin indeed who could stand against a hokage's abilities.