The only JPG file that is available in the generated outputs is the 3D texture. The .MTL file acts as a translator between the model and the OBJ file. It very easily could be reversed since it is not supposed to be viewed on its own, but as part of that set of 3 files.
The GeoTIFF is the georeferenced output at full resolution and will be in the correct orientation for North Up viewing.
You might want to look at the KMZ file in Google Earth and create a lower resolution JPG snapshot from there.
We will look into adding a smaller version of the stitched output to the list of output files.