One might think of Aspergers as a neurological variant that has a faster, more complex, or more sensitive neurology. This can result in a higher level of anxiety sometimes even exceeding discomfort to levels of pain. For children life can become a narrow focus of avoiding what is uncomfortable.
Often neglected are skills to "push through" discomfort. When a child grows into an adult without the skills to tolerate occasional discomfort, he can find himself circumscribed to an increasingly smaller territory.
As a parent, one might try to remedy the developmental deficiencies through bribery, exhortation, or logical appeal. As your son ages, he may begin to appreciate the hindrance his lack of skill imposes on him and be willing to take small steps to expand his skills.
If approached as a program of experimental steps, he might be enticed to attempt to broach the uncomfortable.