Right but this is an easy win for Starmer. Something very unpopular you can scrap, that is costly, that even if you’re a bigot you can recognise isn’t working, etc. That’s something you can instantly do to create the impression you’re very different to the previous party. And the impression, per your comment, is impactful. It really doesn’t say much one way or the other about more important policies (e.g. like the Tory cuts that he said pre-election he would not axe).
z spellings are pretty English, fwiw. The s thing only came in pretty belatedly, from the French. Z spellings are still very common in academic writing; OUP requires it in their style guide. There’s no defence of defense though.