Broadly speaking, if someone says "we should severely curtail gun ownership because at a per-county level some counties have very high firearm mortality rates," it does seem reasonable to me to object on the basis that:
1. in terms of the intersection of quality of life and foundational rights, I care more about the rate of homicide, not gun mortality (which includes accident and suicide). Rights imply responsibility, so the appropriate question is whether people are capable of being responsible with their rights. It is irresponsible if you harm others with the exercise of your freedom.
2. on the basis of individual cities and towns, high gun ownership (freedom) does not seem to correlate to higher homicide (irresponsibility). That phenomenon seems restricted to dense urban areas where gun control is already in effect, and other geographies -- mostly poorer regions where stronger gang and drug enforcement seems warranted.