I don't pretend to be an expert in City politics, but I believe that there would be grounds for a lawsuit if the City could be shown to ignore a Proposition. Certainly, I would assume that the grounds are reasonability - not "fight to the death".

Bear in mind, too, that the City did try to get it struck off on admin grounds as it was being proposed and I believe a court agreed that it was unconstitutional, but that the law didn't allow for a Proposition to be preemptively stuck down on those grounds.