We swallow bacteria all day, every day. The bacteria she’s referring to, though, aren’t harmful. They’re her own oral microfauna and, except for plaque and cavities, they’re mostly harmless. Although microfauna populations can shift, odds are that exactly the same kinds of bacteria will be reproducing overnight, every night.
Some bacteria can survive in the stomach, but most can’t. Helicobacter pylori is one, and it can cause stomach ulcers. Others have been found, but whether they can live there, or just survive while passing through isn’t known yet. It is known that the kinds of bacteria that thrive in the mouth don’t do well in the stomach. If you swallow those bacteria, they die, die, die.
What you have to look out for is bacteria in your food and bacteria and viruses on your hands. Microbes on your hands can be transferred to your eyes, nose, or mouth. If you want your mouth to feel fresh before put food in it - shrug. It’s not going to hurt you. If you’re trying to keep healthy, wash your hands a lot.