It’s hard to say only because they don’t tell enough about the program and how it works. Do you know anyone else who uses the program that you could look at it? Of course you would know best what works for your son. I don’t see any harm in picking a topic or allowing a child to pick a topic and writing on it. And of course there are different forms of writing he could do. And if having some guidance (curriculum) will help with this, I don’t see any harm in it. Just don’t be bound by the method of the curriculum – bend it to fit your son’s needs. 🙂