You've highlighted nicely problem with the phrase and shows that it has misunderstood evolutionary theory.
It tends to apply subjective human values to what constitutes fitness - small may be fitter in certain circumstances - size or strength or intelligence may have no bearing on fitness in nature.
The reality is that ToE would say something like - "survival of the just fit enough"
You are right but don't waste time trying to convince SAM; she has made her mind up. As you say, fitness in the Darwinian sense, is a question of how an organism adapts or fails to adapt to changes in its environment.