Clickbait title. The only germs loving diet soda would be the potential shifts in gut biome as a result of saccharine consumption, which would only apply to Tab.
"The scientists also fed a small group of healthy people saccharin-sweetened drinks for a week. In a subset of volunteers, microbial shifts occurred, accompanied by mounting glucose intolerance. So for some people, diet sodas may not be any healthier than regular sodas."
"Dietary trehalose enhances virulence of epidemic Clostridium difficile"