I bet a strontium-sufficient person has more like 5-10 grams of Sr in them not 325 mg as the article stated.
As with Iodine sufficiency, such a person would not absorb radio-iodine so quickly if exposed. An Sr - sufficient person would also seem likely to not absorb Sr-90 either.
My personal view is that 99+% of the population are just as deficient in strontium , as they are iodine.