I cannot find anything that states other that a LEO can direct traffic. If I had to guess, I would say that if something would happen, the person directing would be subject to charges as well as the motorist at fault. No idea what the courts might say. If someone other than a LEO was directing traffic say, at a crash scene, I would venture the courts, and probably LE, would take the discretion not to file charges. The person was acting in good faith in a dangerous situation. Totality of the circumstances applies.