I imagine Ron will come back with more details, but I can give you the short answer: There's no need. It's a waste of time and money. In addition, it just doesn't work as well with a Cl emulsion.
Azo is a very slow contact printing Cl emulsion. Its claim to fame is that it's beautifully "clean", i.e. the whites are white, or at least close to the color of the paper. The emulsion doesn't need speed, and speed is the only reason to add gold and sulfur. Gold sensitization almost always contributes a tiny bit of base fog, which can actually be a fine thing with film, but is disasterous with paper.
A Br emulsion is inherently faster that a Cl emulsion, even without sensitization. With a BrI emulsion, one whose reason-for-being is speed, gold can be worth the extra effort and money involved.