The aircraft involved wasn't a Pitts Special, it was a SA-750 kit plane.
here is the accident record on the FAA website (record #2). The RC plane was a 46% scale "AJ Slick" aerobatic / 3D model from the 3D Hobbyshop range of model planes.
IMHO the pilot of the SA-750 was lucky to only impact the balsa / lite ply structure of the model plane as a direct hit on the 150cc petrol engine would doubtless have caused enough structural damage for the outcome to be far worse.