Because the claim is that SF violent crime got worse, which is false. You are resorting to comparing the general disparity in crime rates between major cities and small towns, which is not unique to SF. Therefore it is an illogical argument.

I have no disagreement with you in your general point or personal preference for small exclusive bedroom communities where poor people cannot afford to live, but the same could be said in comparison for Miami, Austin, Dallas or any other major city.