I have a different take on this than most (well other than Ivory Tower). In general, I feel that many adults are afraid of bringing up tough topics with teens, thinking that “they won’t trust me anymore” or “they will never speak to me again.” I say this is not necessarily true. If there is something that you think needs to be said, say it. Teens are nothing to be afraid of, especially if you think that it is an important topic. Yes, teens will piss and moan when you as a parent have something to say that they don’t want to hear, but tough. What is the alternative? Some people think that kids raise themselves, that they “find their own way.” I say this is silly. It is our responsibility as parents to actually parent. Some parents go out of their way to avoid discomfort- which unfortunately is a part of parenting. In the long run, teens appreciate boundaries and guidance.
And this general notion of “well, that is what kids do, it is normal, don’t worry about it” is not necessarily true either. Yes it is an expected innapropriate behavior, yes most kids do it, but it is the time for parents to be parents and capitalize on this “teaching moment” to redirect the kids towards more appropriate behavior. It is not unusual for 14 year olds to call each other “faggots” “bitches” or say that they “suck dick” in an apparent harmless teasing fashion. Just because this is normal behavior, it is still innapropriate, 14 year olds still need guidance. Someday they won’t be 14 year olds. They will be 30 year olds. They may think that you are an idiot now and ignore you, but hopefully they will take what you teach them now and use it as adults.
The teen used your computer, you stumbled upon it accidently, you read some kid giving their kid the business, this might be some info that the parents could use, or maybe they think that it is not important. In any event, I think that you should give the parent’s decision how to use the info. Of course, I don’t know the whole story, your mileage may vary!