This article is too far off to let it stand so here goes:
Salt: The author is more than correct in talking about limiting processed foods. I won't even go into unprocessed sea salt vs table salt. As to the rest, you simply cannot pick 2 things like salt and calcium and randomly compare what happens with varying intake without taking a million other confounding variables into account. The key is BALANCE! The vast majority of women eating SAD and thus high salt, are woefully deficient in magnesium and all other minerals/nutrients involved in bone building. What was their Vitamin D intake? Close to zilch I imagine. Most likely, the women who had lower salt intake had much higher magnesium intake because they were eating a more whole foods diet and therefore getting more nutrients. This is conjecture because I don't have the study to look at. Bottom line is that although the bones have more calcium than anything else, it is not really the determinate factor in bone health. Eat a whole food diet, get lots of vitamin D and magnesium and probably salt won't matter much. If your diet is correct, the body won't be pulling calcium from the bones and excreting it in order to balance all the other minerals.
Caffeine The only reason for this effect that I can find is caffeine's diuretic effect. When you urinate, you do lose minerals in the urine. Adequate fluid and mineral intake, in the absence of kidney disease or pituitary problems, usually negates this effect. Again, the women studied were most likely eating SAD and woefully deficient in nutrients. 6mg is minuscule and I can't see how it could result in bone loss unless someone was consuming upwards of 600mg/caffeine per day with no calcium intake.
Vitamin A If looked at only from the standpoint of Vitamin A intake, it does appear to weaken bones. What was not considered was Vitamin D. In an A ratio greater than 10:1, Vitamin A definitely can cause problems. Her advice on how to fix the Vitamin A problem is outrageous: What to do: Switch to low-fat or nonfat dairy products only, and eat egg whites rather than whole eggs (all the vitamin A is in the yolk). Also check your multivitamin, and if it’s high in vitamin A, switch to one that isn’t.
I really hate studies/articles that draw conclusions from spurious data and too many variables unaccounted for.