I think Person1’s point is that of all the Halachos of Loshon Hora, this is not the main one people need to know about, and he felt like you were b’davka choosing to educate people in this halacha, as opposed to all of the others. However, to be fair, you hadn’t really brought it up on purpose – it just came up in the course of the discussion.
To be honest, though, I wasn’t so happy with this discussion taking place on my Shmiras Halashon thread 🙁 and would have preferred that it take place elsewhere.
In any case, I am happy to debate the sources and will do so bli neder as soon as I have time and can find a way to locate them.