In what way is Bitzer a success story of Mr. Gradgrind’s method?

Bitzer comes from Gradgrind's school; he begins as a bully, but he learns the lessons of Gradgrind's "rational," and thus non-emotional education to become a success by Gradgrind's definition.  He ultimately works for Bounderby, but finds himself in an awkward position when he discovers that Tom is the bank robber.  He chooses to let Tom flee, even thought that is somewhat against the rational system of thinking.