Rapist yes. Child rapist I can't get there. None of her actions indicate she was a child. A teenager trying to act like an adult in an adult situation, yes.
The two things I struggle with are:
1. I didn't really like the part where they send "he should have known she was underage". How is that? Because she said she was in high school? No shortage of 18 year old high schoolers out there. I'd certainly be more careful if I were him (though that doesn't seem to be his MO), but that part just seems to be oddly intentional.
Also just one of my pet peeves of "hey this 17 year old is so innocent and sweet", but the 18 year old is somehow fully capable of being an adult, make own decisions, etc. We could be talking like a one month difference in age, and we treat them in totally different categories, based entirely on essentially an arbitrary number.
2. I would think there's some sort of charge coming for having sex with somebody, regardless of rape or consensual, and not disclosing you have an STD. Pretty sure you can't bang a chick, even with protection, wait until the next day, and say "o by the way I have the Clap". Pretty sure that's illegal pretty much everywhere. I'm guessing its a misdemeanor, but I would think that alone, which he confessed to, would warrant criminal charges.