This was an issue on r/nz, that they solved with flairs. No flairs here so I think an NZ politics community is a good idea, so that people who don't care about politics can just avoid it if they choose.
Yes, I think that makes sense. There doesn't seem to be a way to move a post to a different community like you would with for example an older style forum/bulletin board, so if it's in the wrong place really our knly option is to lock or hide it and ask for a new one to be created.