Which is a point made in the article - the technique is not meant to be hard to detect a la cryptography, it's meant to be non-obvious to spot. By exploiting th

Which is a point made in the article - the technique is not meant to be hard to detect a la cryptography, it's meant to be non-obvious to spot. By exploiting the fact that nobody is going to look through (or edit) machine instructions for patterns in register bytes, you can include a message that is easy to overlook.