Getting raped does not "improve self esteem" for anyone. He would not have reported the crime if he felt comfortable with the encounter.
Just on a technical point, it was apparently deemed by a jury not to be rape, or a crime.
And I don't think we can assume it didn't boost his self-esteem. It could have.
Apparently, he told a friend, a girl. It's reported that she told him he was an idiot, and she told his mum, and that's how it came to be reported. That the girl called him an idiot (it is reported) suggests he might even have been bragging (although not necessarily, obviously). And after it came out, a boy in that position might easily retrospectively change some of the details of what happened.
Anecdote: my dad was taken advantage of by a woman in her mid 20's, when he was 14. It happened in a field, under a tree (it was rural Ireland in the 1940s). He told me this when he was in his 80s. We, as a family (mum, dad, my sisters and I) used to quite regularly go visit the home farm, where he'd grown up (his brother still lived there) and he admitted that he secretly used to drive past the field on the way, to remind himself fondly of his first, memorable, sexual encounter. My dad was the kind of person who had what we might call certain appetites, and as such he may have had them quite young. I think that to some extent the psychological reaction depends on the boy in question and what exactly happened.
That's not to say the OP events were not dodgy.
