"Earthquakes have been linked to geothermal power plant in other parts of the world. But the Pohang quake is by far the strongest ever tied to this kind of plant — 1,000 times mightier than a magnitude-3.4 quake triggered by a plant in Basel, Switzerland, in 2006."
If you take the word `purely` out of your statement, it is a political decision. Seems to be based on science though. Everything else becomes irrelevant. This also reminded me about the `fracking` debated in US. If I am understanding this link  correctly, it's not the fracturing of the rocks but the high pressure liquids that induces earthquake? I am still unclear on the detailed mechanism.