Autistic boy scratched me

My son has autism and attends occupational therapy once a week to help him with fine motor skills. It’s 1-1 with the therapist and I wait in the waiting room for him. Around the time I wait, a mom comes in with her son who is probably 5 or 6. He’s appears to be nonverbal and severely autistic. But the entire time he is waiting there with his mom, he runs up and down the waiting room and growls/barks at people. She just sits on her phone unbothered. Today he got in my face and barked and then scratched my back with his fingers pretending to be a dog. Luckily I had two shirts on so it didn’t draw blood, but I think if I hadn’t been wearing flannel he would have caused me to bleed. I turned around and said “no sir, we do not scratch people.” He stated at me and just continued to bark. Finally his mom came over and was like “come on, Elijah, come over here and watch your tablet.” Like she didn’t say anything to me or acknowledge her son just harmed me. I’m not trying to be insensitive or dramatic but my husband thinks I should let the front desk staff know so that they can say something to the mother. What should I say exactly? Am I wrong to be bothered by this? I know my son can get wild in public but he’d never ever harm someone.