No, she is 100% correct.
If you're vaccinated for measles, or have NI from having contracted measles, and you walk into a room full of measles patients, you WILL test positive for measles with a nasal test because you WILL inhale the virus.
Testing positive is irrelevant; the question is are you sick or contagious, and the answer to both in this case is "no".
Same with the flu.
Same with any other contagious virus.
Same with Covid-19.
Tests are a scam and don't provide real disease experts with any useful data.