I think people are congratulating him because he's 18yo and had his first sexual experience with another person and he enjoyed it. To be honest, if he were my son and shared that with me, I would definitely mention using condoms for intercourse and warning him about putting himself in situations where he may be accused of anything, but I would thank him for being open with me and congratulate him on his first sexual experience as well.
No the sex he had wasn't "safe" per se but it also wasn't "dangerous". I would be a hypocrite if I started to chastise him for something that occurs in my own life. I presume Marley and Ms. Teacher that every person you've engaged in oral sex with has been using protection and that you knew each of your partner's histories and had proof of what they say--because people lie.

Yes, std's are very much a reality of the world. But reasonableness needs to enter the equation as well. People are going to have sex, few people will use protection with oral sex and few people will ever truly know their partner's sexual histories. The only truly safe sex is masturbation or someone would have to choose celibacy. I'm not going to stop having experiences because of what if's. Who would leave the house? There are what if's with a million things and can't be bound by fear.

But sexually his experience isn't any different than the majority of people's experience in the world--so if you're going to chastise him, then you're going to chastise everyone, repeatedly and grab yourself a mirror, cause you might need to have a real heart to heart with yourself too.

The house I live in is made of glass, you people who live in houses made of steel are lucky--your foundations are unbreakable but I'm afraid it makes it difficult for you to truly see what's beyond your walls.