He's not. Artificial sweeteners are one of the most demonized additives on the planet despite being one of the most studied. Because people are so often looking for a reason to get rid of them.

Even the studies of them being bad for "getting used to sweetness" and thus making people more obese through compensatory over-eating are studies that rely on self-reporting and polling.

When properly controlled, physics works as it always has and you can't magic mass or energy out of thin air.