I think the ruling is good for one thing: To out a lot of the self-styled GRA as the hypocrites they are.
How many pages did we have were GRA's argued that the problem of a lot of gun legislation is that operates on technicalities, ie on magazine sizes, and that gun legislation would be much better if it were aimed at capabilities.
Thing is, the bump-stock ban is clearly a capability-based legislation. It clearly aims at restricting devices allowing semi-automatic weapons to achieve a rate of fire in the hand of untrained[0] personnel that otherwise is only achievable using automatic weapons, and none of the technicalities fielded so far for justifying the ruling can deny this.
Furthermore, none of the statements offered so far can offer a convincing argument reconcling the very literal, technical reading in the small (the exact technicalities of how a bump stock operates, instead of what outcomes it provides) with the type of interpretation-at-large reading of the Second Ammendment required to sustain Heller.
[0] Things like the "Mad Minute" thing are, at best, an irrelevant trivia, due to the level of training required. Every single fucking university-trained chemist knows how to make Sarin, because there is a bog-standard undergrad reaction that if done wrong produces Sarin directly, and several others that if done wrong produce precursors that can result in the real monty if the stars are "right"; yet no one doubts that outlawing the posession or production of Sarin as a CWC Schedule 1 compound is a good idea.