Hmmm... thanks guys.
For the record, I have tried to funnel all the fantasy play into stories- without success. I tried having him dictate the stories to me, and also tried voice-to-text software... but it definitely seems like it's the process of committing his words to a specific form (rather than the physical act of writing) that causes the problem-- turning an obviously therapeutic activity (fantasy) into unbelievably counterproductive distress.

He is certainly at least at grade level.

I guess it's the unwillingness to sit down and do anything that bothers and worries me.

Also, here in NYC the homeschooling requirements are fairly strict... I would have to significantly fudge the truth in order to unschool.

Which is no big deal I guess. I'm a scofflaw just like he is...