What advantage does a mountaintop have versus a more accessible earth-based location?
I suspect one of the motivations for space datacenters is to try to stay out of the reach of all jurisdictions so you Musk can start to run his companies as an autonomous state.
If the goal is to avoid various national jurisdictions, what about floating a barge out into international waters? Do it near the equator in the middle of the pacific to maximize the difficulty of humans getting there. Use the money saved by not needing to launch into orbit to purchase massive gun turrets to prevent piracy.