In this case, I don't think that the reference is anything to be really concerned about. The author of the article is indeed quoting what a police officer had said; there is no real connection to the game or being bad, it's just a connection between the archaic weapons and the game. Now, if the author tried to tie in more connections with Dungeons and Dragons by hinting that, because this man played our game (which apparently he does not, but the author could "speculate," which would just make it much worse), then there would be a problem.
However, since there was a connection made between the crime, this nut, and our game, it does add a little more to the stigma against Dungeons and Dragons. It isn't a direct link, but there is some association being made there (crazy nut uses archaic weapons which are prominent in Dungeons and Dragons), and any association towards negative events is bad. It goes into pyschological elements; negative associations are bad if you want something to be good.
I don't believe that this will be much of a problem, and I don't think anyone should be concerned with it. It is a very mild association with the game we all love, and it won't have much publicity. But, if you choose to take action, make sure that you are extremely polite and nice about it so we don't have even more of those negative associations.