I will say with regards to the original post. That with respect to a paladin I have told a player that they are playing their class wrong by not following their oath and have taken away theirs abilities until they atoned. I felt that was pretty fair. Those are pretty broad oaths. But burning down a peasants house with them in it to get to the Dark wanderers seemed like a violation of the devotion oath to me.
You know, I think that is fair.
Paladins are tricky beasts, and I've been avoiding talking about them for some time on this thread because I think the mechanics and lore are not only tightly entwined, but held over from previous assumptions from previous editions, and that makes them hard to talk about.
I might yet again be told how wrong I am, but I did play a paladin character for a while, and I took a mildly different route with him.
He was a Paladin of Helm in the city of Neverwinter (The DM specifically told us to make characters connected to Neverwinter and wanted to have most of our adventures in the city), and I wanted to play him as an Ancient's Paladin, because Helm is quite an old god and I know the party I was playing with. I needed the most elastic oath I could get. But, I added to the oath as well. He was a half-elf and had lived through the Cataclysm, in fact due to the timelines, he grew up during that time, where the city had erected a slap-dash wall and was constantly fighting off abominations that were boiling up into a ruined part of the city. He loved his city, he had fought for his city for years, and so I added to his oath parts about protecting Neverwinter and her citizens, because as part of the City Watch, that was important.
That being said, even playing loose with the oath and the attitude, I still had to let things pass, because the party was not going to accept me stopping them from doing certain things. So, I didn't raise a fuss about some of their actions, even though I saw that my character would.
So, to summarize the point I am trying to make because I realize this example is twisting in on itself. Oaths can be very subjective to the players, the dm, and the person whose character it is, but I think in your example, that shows a clear violation. But I've seen other examples of paladins "breaking their oaths" that I would say did not actually violate their oath. It requires finesse and understanding generally to thread that needle