While I realize that you are trying to be helpful but a little knowledge of how thing actually work to help someone get the most from the MC will go a lot further to help someone not only get the most from the MC but also to help them have a easier time of it.
Chewing does activate digestion and the main working MO of any form of fasting is to give the digestive system a rest so from the git go you are affecting fasting main working mode. Here's the clincher. One of the main things that helps folks stay on a fast is the end of hunger. That will only happen when digestion ceases which happens around day 3 +/- If you keep digestion going by chewing gum the hunger will continue throughout the fast making it even more uncomfortable and harder to do the fast in the long run so the bottom line is you are neither helping yourself nor others by telling them it's OK to chew gum when fasting. If fact you are only making it more difficult to stay on the fast. Think of it as scratching an itch. You may get some immediate relief but in the long run you only make matters worse.
The above are the more immediate points to help someone succeed not only by getting the most from the MC but actually help them have an easier time of it. Then you have the chemical crap that you are putting into a system that you are trying to cleanse. If you want to take it further do yourself a favor and do a little research on artificial sweeteners since you specifically mention "sugarless gum". In particular research aspartame.