I would definitely consider it a neurodivergency. I'll explain why based on my understanding of neurodiversity and the DSM-5: In the DSM-5, Childhood-onset Fluency Disorder (stuttering) is considered a Communication Disorder, which itself is a category of Neurodevelopmental Disorder. All of the Neurodevelopmental Disorders (eg. Autism, ADHD, Tourette's, Specific Learning Disabilities, Dyspraxia, Intellectual Disabilities, etc.) are considered neurodivergent. Since Childhood-onset Fluency Disorder is a Neurodevelopmental Disorder, of which all the others are neurodivergencies, I can't imagine it wouldn't be considered a neurodivergency as well. Not all stuttering is neurodevelopmental (Adult-onset Fluency Disorder is psychogenic), but neither are all neurodiversities (eg. Anxiety and Depression).