None of your 1-3 are required. Perhaps this is what led to the comment on lack of imagination?
There is no excuse for an arrogant and condescending comment like that. Why do you continue to make excuses for him?
Perhaps the NPC noble doesn’t recognize the PC at all. Perhaps he decides to grant an audience purely out of curiosity? Or purely to see what leverage can be gained? Or out of fear of what the repercussions of not granting the audience could be?
To respond to your questions one at a time.
1) That is possible, depending on fictional circumstances. It is not something that is going to override fictional consistency, though.
2) Leverage from some minor noble from the other side of the world? There's no leverage to be gained if the PC is telling the truth.
3) Fear of repercussions from turning away a minor noble from the other side of the world? There's nothing to fear.
Maybe the noble thinks such traditions of etiquette are outdated but feels obliged to honor them because not doing so may cause scrutiny he wants to avoid. Perhaps he only wants to grant an audience to this stranger because he thinks he can convince them to do him a favor. Orthat he can otherwise manipulate them to his own purposes.
Those customs are almost surely not going to be the same on the other side of the world. He's unlikely to even know them.
Or maybe he just wants to host a guest from foreign lands that would spark gossip at court.
Like the response to #1 above, this depends on the fictional circumstances and the background ability does not override fictional consistency.
Or any number of other reasons that have nothing to do with magic or friendship or giving the PC exactly what they want.
There area myriad of ways to make this work.
And as long as they are consistent with the fiction, I'm okay with them. A minor background ability does not override fictional consistency, though.
They are minor. They come up so infrequently, according to nearly all accounts shared in this thread. All the more reason to try and make them work. Have that player choice matter.
Not all accounts. I shared that they would work anywhere in the home country as well as any neighboring countries that are not enemies. PCs generally don't travel all that far until mid to high levels, which most campaigns never reach. The ability can see constant use as nobles are everywhere.
What rules would you invoke along the lines of fire immunity that would make this action not work?
To work it has to do 8d6 damage. Fire immunity means no damage, 8d6 or otherwise.
Because your “fictional circumstances” read much more like personal preference.
They aren't.