Frankly, this is not the place nor the context in which I'd like to see this issue come up.
One: Is this a precedent? Yes, in the sense that it is a judicial ruling of law. In theory, all judges should rule the same way on the same question of law, and so this is a statement by this judge that not only should he have ruled this way, but all judges should rule the same way on the same issue. On the other hand, had the matter gone to trial to a jury and the jury returned a verdict of not guilty, that says nothing about what other juries should do in other cases.
Two: Item One begs the question of what the reach of the precedent is. In our hierarchical system, if a higher court issues a ruling on an appeal from a ruling of a lower court, the holding of the higher court is binding on the question at issue in all of the lower courts whose decisions are reviewed by the same higher court. A District Court in Massachusetts does not review the rulings of any lower courts, and all of the District Courts are hierarchically autonomous. As a result, this decision, while a legal precedent, is not a binding precedent on any other District Court (or even any other justice of the same District Court).
Three: As I pointed out once earlier, Bolduc's argument raises two issues. Issue #1 is the "incorporation" issue: Has the Second Amendment (which, by itself, applies only to the federal government) been "incorporated" into the Fourteenth Amendment, so as now also to bind the states? Issue #2 is whether, assuming the Second Amendment applies to the Commonwealth, is it offended by the "storage" provisions of the Massachusetts statute?
As to Issue #1, I'd as soon see this resolved anywhere other than in court populated by a judge or judges who come from this neck of the woods.
As to Issue #2, I think Bolduc's argument was wrong. In Heller, the Supreme Court invalidated a "storage" statute because it required storage at all times, thus precluding a "readiness state" for defense of the home. The Massachusetts statute, on the other hand, authorizes carrying of the firearm on one's person in the home, and thus permits the "readiness state" that the Supreme Court found constitutionally required. The Massachusetts statute requires secure storage only once the gun is removed from the hip. As a result, the Massachusetts statute satisfies the Heller rule and is not invalid.
Four: What of the future? Since the dismissal by judicial action is a ruling of law, the District Attorney, if so inclined, could seek to have a higher court review Justice O'Neil's ruling. For the foregoing reasons, I do not view that as a happy prospect. How likely it is to occur I cannot say.