He won't respect you simply because you're a manager. You have to earn his respect.

This is good practice even for non-autistic employees, but… it’s reasonable to expect that an autistic person knows that there is a hierarchy to their job. Depends on what you mean by “respect” here of course, but mild autism that still allows you to work in a professional setting is not a blanket excuse for being disrespectful to coworkers or managers.