Interesting point.
If the Earth is unique, or at least very rare, then that is an answer to “why aren’t they here” about extraterrestrial intelligence.
On the other hand there doesn’t seem to be a direct or indirect connection between the prevalence of heavy metals and the formation of life or the development of intelligence.
Agreed. I don’t know what the impact would be, but when you think about it, how many movie aliens have you seen that wore gold bling?