Interesting. It could of course be that Coldplay just chose the wrong picture. When people see the painting, they just think “The French Revolution” and that’s it. At first, I couldn’t really get it to fit either, but this article was interesting. I do believe the King did hope St Peter would call his name, but the lyrics are not that far off.
https://clarifyingcatholicism.org/2021/01/26/the-good-king-louis-xvi-as-a-religious-figure-and-martyr/?unapproved=3609&moderation-hash=a3dff49dd0cdea98a967bed28ebb5e38#comment-3609