I just can't fathom how saving the trees is worth leaving a stockpile of metals undiscovered.
Sure in Legacy's view overproduction in metal could lead to a catastrophic disaster.
Because, the ability to use metal is dependant on wood.
The more metal you have, the more trees you need to melt it down & forge it.
So, if you have no trees, then the metal is worthless (apart from as a trade good), as you can't do anything with it.
All you've done is swap a deficit of metal, for a deficit of wood.
You can live without metal.
Without wood, you have no fire. You can't cook without fire. You catch illness, e.g. hypothermia, without warmth from fire.
Aside from that, having a deficit of trees is far more detrimental to the environment, which is obviously therefore more detrimental to organic life forms.
No more forest = no more animals = more farming required to feed people = more metal required = more wood required - shit, no more forest!
It's a vicious circle of exponential consumption.
Not to mention the fact that they remove carbon dioxide from & produce oxygen for the air we breathe.
I think Legacy's looking at the long-term impact, not just the immediate.
However, if a war breaks out and those metals get into the wrong hands things could end up just as bad.
Didn't Zaya's Mother say to MC about how they don't have the knowledge or skills to do anything decent with metal?
The crafted items that Uncle brought back, e.g. the spears, were incomparably better than anything they could produce.
They also seem to have quite a lot of it, already. The amount they brought to secure passage to the island wasn't small.
It's why they were so willing to trade it, with Uncle, because their smiths and forges are not much good, so the metal has extremely low value - to them.
Things have different value, in different circumstances, dictated by supply & demand.
e.g. If your community has no forge & no smith, the chunks of metal are of limited use, therefore limited value.
Supply is plentiful, demand is limited = value decreases.
Metal had no real value to the Remnants, but people did.
Vice versa for Uncle & Ecclesiarchy, with Exiles, hence trade.
The AI's also told us that there are considerable amounts of metal deposits in the ruins of the cities.
Any group from the Remnants' island could easily already have access to large amounts, so I'm not sure how much threat it getting "into the wrong hands" carries.
Particularly not, if they do not have the capability to use it with any proficiency, as per The Remnants.
The Raiders we've met do not seem to have much in the way of intellect, so it seems unlikely they'd be any better at forging, or smithing, than The Remnants are.
