The headline is misleading - there is nothing "landmark" about trying to ignore the 2A - ACF*-run city governments try this nonsense all the time. It will fail judicial review as all the others. This is settled law. You can't force specific people to buy things they don't want to buy (like unnecessary insurance) or levy taxes on specific groups while ignoring others, simply because some people in government decide they hate those people. 

Forcing all people to buy car insurance is utterly and completely different from trying to force gun owners to do the same. To operate a firearm safely does not incur excessive liability because the odds of a mishap from using firearms normally are infinitely smaller than those of using a motor vehicle. 

Firearms are very safe (statistically speaking) when handled legally/correctly - motor vehicles are not (because the average frequency-of-use is hundreds of times greater for driving cars than using firearms). IOW people drive cars every day for hours while most people use firearms no more than a few hours per MONTH.  

Flies constantly buzzing around even though one keeps shooing them away. 

The idea of taxing specific groups as a punishment will not fly either - a tax must be uniform (not targeted against small groups) and be established with rational criteria - such as to pay for required services/administrative needs generated by the activity. There is no strong evidence that owning a firearm is something which requires any government action other than from the documentation processes already in place - so there is no basis for levying an extra tax or charging extra fees. 

Such a capricious, vindictive things is similar to the muzz "fey" which is how muzz governments force non-muzz living among them to pay money just because they are not muzz. Forcing people to pay a tax just because they own a gun (IOW, are not opposed to private gun ownership) is using government power to target political enemies - i.e., fascism. 

* ACF = Anti-Conservative Fanatic