a) Let him get on with it in order to keep him quiet, but knowing that he's probably annoying everyone, and that it looks like you have no control over him.
or
b) Stop him, knowing full well he's going to scream blue murder, and that it looks like you have no control over him.
Ds (16 months) found the toys, but insisted on throwing them around, and offering them to all other patients, and depositing them all over the waiting room, with me trailing pathetically after him.