Yes, it's what you think.
I have mixed feelings about this. I grew up with a lot of things going on in front of me that I shouldn't have seen, though it mostly involved the consumption of certain illegal substances instead of sex. I did walk in on my mom and my step-father once. They weren't having intercourse, but it was clear that it was the intended conclusion. I didn't ask questions because, quite frankly, I had seen worse in porno movies by that point.
Personally, I am not a big fan of doing the dance of love in front of my kids, nor am I a big fan of doing "illegal substances" in front of them either. Do I think people should be thrown in jail for doing these things? I really don't know. That stuff happened in front of me and I turned out okay. Is it the government's job to ensure that people are "decent" parents, whatever that means?