> As with other HTTP error codes, the real answer is that one should probably use whatever status code is most convenient.

That's all you need to know. HTTP, like the other components of the web stack, is an organically grown monstrosity that resembles what you would get if a thousand random people shat on a pile. Any attempt to extract philosophical purity and/or rigorous discussion from it is a massive waste of time. Just use what you feel makes sense at the current moment, and move on.