Yes that's true, but compared to stainless and carbon steel it may only contain trace amounts of the metals that are the focus of this study.

Everything in the study is trace amounts!

I don't think they're really comparable though. For example: Stainless steel contains 10.5%+ chromium. Carbon steel contains up to 10.5%. Steel (with a non-trace amount of chromium in it) ends up leeching trace amounts of chromium into food. Some cast iron probably has trace amounts of chromium in it, but far less than the 10%+ in steel.

This may also leech chromium into food, but most likely at an even further insignificant amount. It's not part of the study and I am not a chemist, so I don't want to make a conjecture.

Chemistry is complex enough that layman cannot make any assumptions. For all we know stainless steel and carbon steel have higher content than the cast iron, but leach less because it's far more stable.

Doesn’t chrome and moly make it stainless?

It’s the chromium. Cookware usually has nickel too. When a pan is advertised as 18-8, they mean roughly 18%Cr-8%Ni. Basically the same as 304 stainless steel. You have molybdenum additions in something like 316 stainless steel.

I think it depends on the amount, though I'm no expert.