Autism after DSM 5: the potential impact in one child's case

Max is a 21-month old boy with speech and language delay presenting for diagnostic clarification and treatment recommendations. Max was born at 37 weeks after a twin gestation. He is medically healthy and lives at home with supportive parents and a typically developing twin sister. Max began speech and language therapy when he was 14 months old.Max spoke his first word at 16 months. He uses fewer than 10 words or word approximations; however, he does not use these words spontaneously to communicate. Max has decreased use of eye contact and rarely uses nonverbal means of communication. Max whines but does not point or reference his parents to request their help when he wants something out of reach. Max responds to 1-step directions about 50% of the time. An audiology assessment was normal. Max does not bring objects of interest to show others, rarely initiates interactions and does not consistently respond to social overtures.Max is described as an easy-going child. He is content to play on his own and shows little interest in other children. He likes to spin wheels for the purpose of watching them. Max has no rigidities or rituals and is easy to redirect. He has no sensory seeking behaviors or aversions. He does not engage in any repetitive motor mannerisms.On formal evaluation, Max's cognitive skills were assessed within the average range; language and gross motor skills were below average. Performance on the Autism Diagnostic Observation Schedule, Toddler Module was concerning for an Autism Spectrum Disorder (ASD).Max's evaluation was concerning for deficits in social and communication functioning. A new Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) was recently published, resulting in a change in the diagnostic criteria for ASDs. Max meets criteria for autistic disorder under DSM, 4th edition, text revision (DSM-4-TR), but does not meet criteria for an ASD under DSM-5. Specifically by DSM-4-TR, he met all criteria under social interaction, 2 criteria under communication, and 1 under restricted and repetitive behaviors. By DSM-5, he met all of criteria A and just 1 of criteria B. How would you proceed diagnostically and what treatment recommendations would you make?