Clearly the judge's decision is based more on fear and feelings than on logic and a correct evaluation of facts.
If the level of force used is appropriate to the situation, the means by which that force is applied is of no consequence. In other words, if deadly force is appropriate, why would it matter if it was applied by a bolt action firearm, spear, select fire weapon, sword or sharpened stick.
The judge's opinion aside, I would rather have a tool designed to do the job of defending myself properly than have to use a big rock. Similarly, I could move a household with a pickup truck, but a large moving van would make the task much easier. So if I am justified in protecting myself from a marauding mob, I would rather have a modern firearm designed for that task, rather than having to use a musket with a bayonet on its end.