You're a retard on this one.
I coach high school boys. A 15 year old boy is definitely being taken advantage of for sex by a 47 year old. There's a HUGE difference between a 15 year old and an 18 year old mentally and emotionally. I see it almost everyday the way they interact with their peers.
Where I would see a 17 or 18 year old possibly bragging about such things, a 15 year old usually won't say anything to his friends about screwing a women 30 years older than he is. The average person finds this whole situation rather revolting.
No 15 year old is dropping their pants for a woman old enough to be a grandmother as their ideal sexual encounter. She sought him out and initiated this behavior, guaranteed.
I don't think he'll be damaged and traumatized by what happened, but his peers around him will tease him relentlessly for it. I'm sure he doesn't feel proud of the whole thing, given she's going to jail and he'll forever be known as "that guy".