Hy, you may have that backward. Rinsing or brushing your teeth should reduce the acidity of your mouth (raise the pH). The mints in question would raise the pH in your mouth, if they worked as advertised.
Think of the stuff that many people eat, and I think you'll come up with a diet that is relatively acidic, be it from fruits, berries, condiments, juices, soft drinks etc. Many salad dressings, mayonnaise, etc have a vinegar base, and certainly lots of canned foods have added citric acid (I think it is added to preserve color in some cases). Popping mints with buffers in them may or may not be a good idea. It certainly would not change my physiology that much, since I make and eat pickles, pickled peppers, and chili relishes with a vinegar base, and love mustards, too. Those little mints wouldn't stand a chance against such a gustatory onslaught.