At the very beginning of HN guidelines we read:
"Off-Topic: Most stories about politics, or crime, or sports, unless they're evidence of some interesting new phenomenon. [...] If they'd cover it on TV news, it's probably off-topic."
It sounds pretty much like a story that could make it to TV news, and the phenomenon itself is hardly new (a number of precedents has already been pointed out in other comments).
Because people complaining about this is tedious and a regular feature, and it only causes noise. If you don't like an article, move on. If you think it's off topic and shouldn't be there at all, flag.
For my part, I find it interesting not because of this specific incident, but because of the comments it has sparked showing how naming places is regularly being used as a low-key passive-aggressive protest by local governments.
To me that's an interesting hack around the otherwise limited powers of local government.
You just explained why you think this should be on HN, something that wouldn't have happened without the question.