I think this is overly simplistic. The idea avoiding contact of fluids with recent trauma might be somewhat supported, I've seen suggestion to avoid brushing teeth or eating particular abrasive foods such as doritos before unprotected oral, but the black and white once any active virus is in you you are infected I don't think is helpful... they say that while neither spitting or swallowing fluids from unprotected oral are particularly safe, the worst thing you can do is keep the fluids in the mouth for a while before spitting, the immune system exists and details matter, swallowing can be better than keeping fluids in the mouth for a prolonged period and the digestive system (like the acid in the stomach) is not that hospitable, especially for viruses that target mucousal tissues found in the mouth and genitals.
