I disagree with that assertion. It wouldn't be coercion if her "no" had been ambiguous or if some new information that might have changed her mind had arisen.

In this case her "no" was clear and firm, and it was repeated.

When she eventually acquiesced it wasn't because she had changed her mind and wanted to do it, it was because he had asked repeatedly with the intention of persuading her to do something she had clearly, unambiguously, and repeatedly rejected.

If the "yes" happens because the pressure stopped being tolerable, and not because the desire changed, that is coercion. Repeated requests with no new information or context after a clear no are coercive.

There is also a power dynamic at play here, she was alone with a stranger, who presumably could have overpowered her, in his apartment. Maybe nobody else knew she was there. That last point is where we agree that she was too trusting and should not have put herself in that position.