This story is probably untrue, the two sites cited appear to be mock-ups of the mtv site and the metallica site hosted under a different domain.
Of course such a suit would have no legal merit as the Canadian band would be able to cite so many other usuages of that chord sequence before metallica were even thought of.
Yes I apolgize for even posting this w/o clicking on the additional links that the story provided. A radio station in Boston reported this story (with the URL) which is why I thought it might be true.