Sounds like Trump is more straightlaced than the model thought he was. She may have thought his parties were a bit wilder than they actually were, and "forgetting" a bathing suit may have been the norm at parties she had been to before, like those at the Clinton household, or Hefner's place.
Actually, the explanation is even simpler than that. The NYT simply lied about what she had to say in this interview. She said the opposite of what they imply. See her Facebook page: