Also remember that most boys (general rule, some boys will differ!) don't seem to be as inclined to want to write as girls. I have boy/girl twins, and my dd will write stories, make lists, write letters, do as many workbook pages as I will let her..... and my ds does the bare minimum of everything!
I just recently started having him try to write very short stories and copy sentences for copywork, and he'll be 7 in about a week. I think you're fine to just keep in simple and work on it in later years when he is more ready (or as ready as any boy can be!)
I'm also a Beechick fan, by the way!
Enchanted Learning does look like a great site, but I'm not a member.