Each to his or her own! I have been fasting for fourteen years, and love to use this simple technique. I have never felt that swishing oil in my mouth stimulates my digestive process in any way. If you swallowed the stuff of course that would be counterproductive, but of course I expell the oil, then rinse and brush and voila! A whole new mouth.
My business is food. I find I can taste foods as part of my job, expell, rinse, and have never had any sense that the digestive process, which I think I'm pretty familiar with, has been stimulated in any way.