That frozen core should work very well as a giant heat sink. I actually got back to the game after this post and started on a magma core for the first time. It is a dramatically different gameplay, very fun though. You have a fairly small time window to find where the magma pockets are in direct contact with the adjacent biomes and close them off, anything that you don't insulate away is rapidly lost to the heat. I have completely lost access to the core, there is only one way down and it is through a 700°C and rising hellscape, which means no oil industry for me for now. This pushed me to finally start messing with the space stuff. Please do ask them questions if you have 'em!
You ain't even a bully enough to send me a pic of your own cock lol