This is of course true - iron, sodium, magnesium, calcium, potassium etc. etc. are metals that are essential nutrients, but potentially toxic in large enough amounts. Metals like nickel, copper, zinc and chromium have roles in trace amounts but again are toxic in larger amounts. Aluminium isn't needed as far as is known but it's quite abundant and likely to be in lots of food products, either as a deliberate additive, taken up from the soil by plants and in the food itself, or by leaching from containers or cookware.
What I was really getting at is that almost anything you use in vaping is going to have something in it that someone is going to worry about. For example, aluminium in kanthal, nickel and chromium in nichrome and stainless steel, or copper in brass connectors. But I can't really see those elements getting from your coil into your vapour in any appreciable quantity. You are likely to get far more aluminium in your normal diet than you'll ever get from vaping IMO.