Actually, Uniform Building Code will not allow for a USDA certified commercial kitchen to be attached to a residential business with a common door. Nor can the water or sewer be shared common to the two units. The reason there is an exception is the nature of the food you are preparing. Not a local code, if you are cooking food for cold storage/canning and commercial distribution, you will not be certified for distribution through a home kitchen.
Pies, cookies and cakes would be considered fresh sale and do not contain spoilage elements. Rubs are dry powders and are not cooked. In a sense, you are both right, it matters what you are certified for.
I'm feeling bearish, and I'm packing a Wusthof Grand Brisket slicer from MABA
"perhaps...but then again...maybe not..."