The amount of aluminum in the clays varies depending on the exact type of clay and where it's sourced. You may be right about calcium and sodium having the same content (as long as they're sourced from the same location). As I said it was just something I seemed to recall.
As for the sentance about Bentonite increasing aluminum content in wine - again, certain Bentonite clays DO have aluminum contents through the roof (up to 80%) which is why you want to be sure that whatever you consume internally is food grade. Still if it only doubled the alum content of the wine you can be sure the vast amount of the aluminum in the clay was retained by the clay.
If the point of the article you referenced is how dangerous the aluminum content of Bentonite is - why does it conclude that clay is so beneficial to the health of animals (which was the scope of the article)?