If it causes you to lust, then of course avoid it. But I don’t see how you’re giving approval to anything. That’s an odd choice of wording. Firstly, how does the other couple know whether you are listening on the other side of the wall? Secondly, how do you know that they aren’t married?
It just seems odd. I’ve never before encountered this concept… of it being sinful to stay in your hotel room if you happen to hear someone else doing what sounds like sex. I would find it annoying, as I said earlier, and if it was that loud I would complain… would have to be a pretty cheap hotel I think to be an issue…