Is it a distribution problem? They can't build enough power cables, or they've already built them over as far an extent as is manageable? I can see how it's easier to just put a big data center on site, but it seems like it would be better to invest differently.
To invest in a data center requires things like reliable property rights, a functioning judicial system, peace and security, network connectivity and other supply chain issues. You want rule of law, peace, security and infrastructure.
The advantage of bitcoin is that once you mine the coins, it is a lot harder for someone to come and take them from you, whether that someone is a rebel group or a corrupt government official or just a local crime syndicate. Moreover you are not dependent on available network backbones or any of the other required infrastructure that a data center depends upon.
I think you misunderstood my question. My guess is that the plan to use the volcano for mining bitcoin is to put a big bitcoin mining data center close to it and powered by it. My question is why this is better than expanding distribution of the power generated to be used for more useful things across the country and region.
My guess would be that those other useful things also require rule of law, taxation capacity, property rights, social organization, etc, in order to be feasible long term investments.