I'm going to have to dig around and do some research here, but.... Now, correct me if I'm wrong, but from what I gleaned on Hojoy's website, she communicates in an assisted manner through a letterboard, no?
If I recall correctly, the research that's been done in these instances shows that the disabled person, whatever the reason they're unable to communicate, generally cannot communicate information that their enabler *does not already know*.
a) she's been unable to communicate in any other way, other than through those close to her, particularly her mother, and
b) her apparently startling early development of language and other sophisticated skills, despite the lack of access to the mechanisms through which language is typically developed (namely, speech and movement),
I can't help but think that her enablers, unwittingly, are the ones who are actually writing these pieces.
OTOH, I'm posting this at 4am 'cause I'm tired but yet can't fall asleep, so I might not be the least bit coherent here. But, if there's demand, I should be able dredge up some more authoritative info than just my spotty memory here :)
(among other things, c.f. Ouija boards.)
Here is my philosophy: Everything changes (the word "everything" has just changed as the word "change" has: it now means "no change") --Ron Padgett