Visual hets are the definition of codominant when talking about ball pythons. Technically, pastels are "het" for super pastels (also known as opals once upon a time) but no one calls them het opal or het super pastel. The reason they are known as codominants is because 100% of the time you know what you are going to get (or have the possibility of getting) when breeding certain animals together.
There are normals with the "pied markers. There are genetically 100% heterozygous piebalds that do not have "pied markers" this means it is not a true codominant and therefor not a "visual het" like yellow bellies, pastels, lessers or any codominant gene.
Justin Kobylka is not the average ball python owner, he is (from what I understand) extremely experienced in keeping and breeding these animals and took a chance with one and had it turn out beneficially for him. Not every "average-joe" will have that happen.