The first part of your post confused me. Your friend doesn't know of his diagnosis, or his therapist doesn't know you two are friends?
Many Aspies don't like to be touched at all, and some need to feel a bond or emotional closeness in order to allow a hug.
Hugs (personal touch) are important for a person's emotional well-being, and as we grow up, many seem to lose that until something reminds them.
If you feel a kinship with your friend because you are both Aspies, but he doesn't know about his diagnosis, he might not be as receptive of it because he won't understand what you are feeling "close" about.
Or, just walk up to him and ask if he'd like a hug. If he says, "No," just know you tried. Don't disclose anything he doesn't already know, because that would be crossing personal boundaries and be inappropriate.
http://health.usnews.com/health-new...les/2016-02-03/the-health-benefits-of-hugging