Fwiw I disagree with this specific suggestion. Flying a domestic leg and dealing with a domestic connection increases your stress level enormously. On the domestic flight nevermind exemptions or fraudulent certificates -- you'll be looking around you realizing that none of the people on the plane had any testing or vaccination requirements whatsoever. And walking around the airport waiting for your connection you'll be in a surprisingly crowded airport where things are business as usual and nobody pays any attention to your personal space. Not saying anything about the real level of risk but it certainly won't make you feel any safer.

My recommendation is to buy some good quality mask that you trust to protect you that you'll feel safe in regardless of what's going on around you. Ideally eat before the airport or in a place where you feel safe in the airport and then don't take the mask off again until you're outside at your destination. This works much better in the Eastward direction overnight than it does heading West though where the flights are longer and during the daytime