Of course the study is flawed...it is only observational. But it is highly suggestive and really, what is the potential benefit of oversupplementation of calcium? I say get it from those food sources, don't exceed 1400 mg from supplements, and get your 15 minutes of sunshine daily!
We just gotta wait for the controlled studies, but I suspect it is inactivity and poor nutrition as the confounding factors for increased heart disease. Relying on supplements is no substitute for the real thing. Weight bearing exercise and good nutrition are the best thing for the bones. Sitting on the couch and popping calcium pills with or without vit d k or whatever...not.