Actually it is about Camille's voiceover line of "Ever wonder how you became an orphan?"
Does A-Sol only have lines relating to people from Targon? No. Does Ekko only talk to other Zaunites? No. Do you think Camille is only going to talk to people from where she is from? IDK, IDK how you think. You know what I think? No.
For the 3rd time, I do not think it is likely that she is talking to Sona. It wouldn't make sense from what we know about their lore as of now. That being said Riot has used champ lines in the past to hint at connections they have yet to make. A-Sol was calling Taric an aspect even before Taric got reworked, when he had absolutely nothing to do with either Targon or the Aspects.
However that does show that Riot has, in the recent past, used champion lines to hint of lore/changes that are yet to be revealed. We also know champions interact with other champions that are from different places. Therefore it is plausible though unlikely that she could be referring to Sona. As Sona is an orphan and we know nothing about the line other than that it is relating to an orphan.
You say I am trying to win an argument about something irrelevant. I am trying to make a perfectly reasonable point, not "win" an argument. If you don't know something for sure, but it is perfectly possible, then it can't be dismissed in a discussion about it. Technically it could be doctor mundo. It is incredibly unlikely but hey, there isn't any reason it couldn't be. Maybe it is a voiceline Riot added in for shits and giggles that never actually plays.
The thing is that you can't say, with 100% assurance, that it isn't one of those things. However they are unlikely enough, and out of line with Riot's normal actions enough, that we can safely say that it probably isn't directed at Mundo since it doesn't make sense. Is it a possibility? Sure. In a discussion is it progressive to bring it up? No.
Sona on the other hand is related. She is an official orphan, and we don't know what happened to her parents. It is still unlikely, but unlike Mundo it would make sense in the context of the line.
You are arguing that I shouldn't bring something up because it is unlikely. That isn't how discussions work. In proper discussion about a topic you bring up all the reasonable possibilities and discuss why they would, or wouldn't, work. If there was something like "We know Sona is an orphan but we already know who killed her parents" then it would be off the table as a reasonable possibility. However as we don't know that it is still perfectly plausible, though unlikely.
Yelling at a person for bringing up something just because it isn't as likely as other options, than calling it "irrelevant" with your only evidence being something that is only possible, not plausible, is honestly one of the rudest things I have seen. Discussions aren't about shutting peoples ideas down without considering them. They are about having a reasonable discussion of why they would, or wouldn't, work. Then comparing that to other possibilities to determine what seems most likely while keeping in mind that it is completely possible it has nothing to do with these. That is how you have a discussion. If you aren't willing to follow proper etiquette when having a discussion then I would rather not have a discussion with you. That being said if you are willing to put aside your attitude, be polite, and discuss in a reasonable way I would love to continue talking. Up to you my friend.