No worries. You're trying to track a pretty extensive collection of information. Believe me, I've been known to forget that I gave the test, let alone received results from someone else!
Other than writing, his achievement scores are very, very good, and correspond quite well with his cognitive profile.
At this distance, we probably can't pin down for sure everything that led the examiner to state that this was a low estimate of writing skills, but I think we have some good ideas. Handwriting probably fed into frustration over the writing tasks, especially those of sentence-length or longer. (Spelling appears unaffected.) I have seen "stuck" have pretty significant effects on Sentence Composition before; I would imagine he refused to complete some of the items in the sentence building portion of the subtest, because he didn't know where to start from. If the other half of the subtest scored well, that would be a pretty good indication that the underlying writing skills were more-or-less intact, even though his formal overall subtest score was lower than expected. Even so, the extended writing task (Essay Composition) is a little lower than I would have liked to see. I don't know how much of that reflects a high-quality, but overly brief, response, as those component scores are not presented here (though they must exist somewhere!).
In any case, this mostly confirms what you already knew about his historical academic experience. I don't think it changes his present substantially.
