Good points.

Some people are better off not carrying a firearm (physical disability, mental disability, logical disability;^), but should not be prevented from being able to defend themselves from aggression. More variety is a good thing.
As for your particular case, you probably want a wide variety of damage levels available so you can choose based on the circumstances. Sometimes just having a shiny (visible in limited light conditions) firearm is all that is needed.

"It is difficult to detect clear signs of use and misuse of stun guns, unlike handguns. Stun guns can deliver repeated or prolonged shocks without leaving marks.."

By this logic, all the more reason that law enforcement should not carry stun guns. We would want signs of excessive force to be obvious.
(edit... qualifier)

Because Ben Franklin wrongly guessed that charge carriers were positive, we now follow possitive 2nd Amendment convention, making it work backwards from what the text says.

I'm unclear why I would want a less damaging method of self defense. If I have to use a weapon in defense I want you down and out.

Yes k, they will have Government as God and you will submit, rot in prison, or die!

yea, those agency swat teams want you nice and defenseless

The question is: Does a citizen have a Right to defend themselves against criminals and government agents? If your answer is yes, then the method used is immaterial. That misuse over time is guaranteed and the founding fathers could not have imagined electrical guns are merely distractions for the inattentive.

Based upon my understanding that the military does not use stun guns, I agree that they are not protected under the 2nd amendment.
However, the Massachusetts law is still an ass for banning a less damaging method of self defense for women in particular.
Maybe someone will sue the state on sexism or size-ism.
Have they also banned pepper spray?

This makes no sense. If you accidentally shoot someone they may die. It is far less likely they die if you use a stun gun. Perhaps it's the word "gun" that bothers them. Maybe they should be shaped like a straight stick and we could call them "stun wands" instead. I wonder if this case will go to the Federal Supreme Court?

"a classic legislative basis supporting reality". What an interesting claim. But, hey, it's Massachusetts, what do I expect? Pretty soon some court is going to decide how many times a minute I'm allowed to breathe.
Edit; clarity

see, I think decisions like these are going to become problematic for assault rifles and 3D printed handguns. "Because the stun gun that the defendant possessed is both dangerous per se at common law and unusual, but was not in common use at the time of the enactment of the Second Amendment, we conclude that stun guns fall outside the protection of the Second Amendment."
What I could have understood was a case that stun devices were not firearms and therefore should not fall under the 2nd Amendment-but the court really did not distinguish on that basis, merely the modernity issue.