Maybe, he isn't:
"The most academically disabling difficulty affecting children with stealth dyslexia is almost always dysgraphia, or difficulty writing by hand. Several factors often contribute to their difficulties with written output...
... They may lack the kinds of visual templates that can be used to form words, or be unable to translate auditory word images into the kinds of signals the motor system needs to form letters. Second, they may have spatial or sequential processing difficulties that make it difficult for them to remember how to form individual letters (resulting in oddly formed letters, reversals, inversions, and irregular spacing)...
...These children are often especially hard for parents and teachers to understand, because they may have verbal IQ in the highly or profoundly gifted range and show every sign of verbal precocity, yet be unable even to write the alphabet--even as teenagers."
by Drs. Fernette and Brock Eide