In short the piece is about novels Art Robinson used in his homeschool curriculum, a curriculum he made available to the public, for a price.
Now I was expecting a classic such as Tom Sawyer or Huckleberry Finn by Mark Twain. But discovered it was a book and author I had never heard of.
A PBS bio of G. A. Henty states that his books "are notable for their hearty imperialism, undisguised racism, and jingoistic patriotism," indicating that they they went out of print for a reason: such attitudes fell out of fashion decades ago.
I certainly wouldn't have chosen to use Henty's work, certainly not all 99 of them. But that is the beauty of homeschooling one doesn't have to use books one finds distasteful or poorly written. If we had read one of his works, it would have been used as an example of the popular assumptions held by the majority of the British people in Henty's own time. And that the British used these views to justify colonizing what they considered to be inferior races.