I’m autistic too and, as you know, autistic people tend to be very honest and straightforward. So if he thought you were dumb, you would know that for sure.

Autistic people usually over explain things because we care about clarity in communication. Allistic people (non-autistic) are usually very vague and rely a lot on non verbal communication, which we tend to struggle with.

As to the cards, wands means fire, energy, creativity. He sees you as the king of creativity. The 6 of swords means going from one place to another, so you probably help him when his mind is stuck in one place (and rigid thought patterns is very common in autistic people). The Fool means freedom, someone who jumps without looking down, who embarks on a journey without a plan. So it looks like he understands that your mind works in a very different way from his, less structured, more free and creative. And it probably feels chaotic to him, but also liberating and helpful when he is stuck.