Exporting .psd to .jpeg changes CMYK to RGB

I know JPEG is not ideal for printing, but when for whatever reason the printer requires a JPEG rather than a TIFF Photoshop is not making it easy. When I want the ease of exporting using the export dialog, the JPEG is ALWAYS converted to RGB. When "Convert to sRGB is unchecked. And I can't see any other RGB-like controls. What am I missing here?