The fact that your son felt the need to tell you about it in the first case indicates that he did, either in the moment or after, feel that something was off with the interaction with the friend. I personally would encourage you to not have unsupervised interactions between your son and the women. I do not see a logical reason for why she would need to put her hand that high through his swim trunks.
The whole interaction was inappropriate.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.