The level of pH difference we’re talking about here is negligible. You’re constantly bathing your teeth in your (slightly acidic) spit and swallowing your spit all the time, the very few moments your teeth come into contact with slightly more alkaline water have no lasting influence. Plain tap-water (also slightly alkaline with a pH of ~7.5 in most of the US) would have the very same effect.
Brushing your teeth after a meal and abstaining from sugary drinks is where the difference is at, Everything else is talking about if Mount Everest is higher when you place a grain of sand on top… technically yes, but no.









And with juuuuust a tiny bit more sugar so the bacteria in your mouth can create more acid to bathe your teeth in way longer than the water remains in your mouth, nice.