I can see where a case like that is confusing. Psychology as a whole is definitely a science and is definitely based on a quantitative and qualitative set of data. Its kind of hard to think up an analogy that would explain why her case doesn't really disqualify psychology as a science.
Everytime you drop an apple on the ground, it'll fall, but I can fake zero gravity by taking you up in an airplane and doing some zero G maneuvers. Then when you drop the apple, it'll appear to float. Does that mean that there's a flaw in gravitation and relativity?