I don't see a problem with how Max acted after seeing the vending machine. Asperger's/Autism has an affect on feeling for OTHERS. Not feeling for oneself. Have you not watched Temple Grandin? Temple Grandin is much more severe than what Max is being presented with. Yet, anytime it was her, herself...acknowledging surprise/gratefulness/joy/sadness came just fine. In other words...watching the scene is funny. Here is a guy happy in himself. He couldn't care less about the joy being thrown his way.