They are a reasonable sized custom brand and in my experience, very good quality and excellent finishing!
But in comparison to GM, Gray Nics, SS, Kookaburra, etc, they are tiny and they would financially cripple themselves trying to attract big players! And why risk it if they are already seen as high quality and can keep up with demand!
If the demand doubled or tripled then the additional outlay to increase production would be mental, not to mention the risk to their high standards and quality they currently have.
And I'm sure they are happy with where they are in the market!