MIT has verified the basics concepts at lower power levels. So while there's still uncertainty and risk here, it's wrong to say it's totally untested. It's trying to make the jump from lab demonstration to commercial viability, which is exactly what you'd expect a research project like this to be doing.
The jump from lab demonstration to commercial viability is exactly the place where almost every tech trick fails.
So there is no need to pay this thing any attention. Geothermal under ideal conditions is not competitive. Steam turbines have operating costs solar and wind do not.
This is the same reason nukes are a dead end, and D-T fusion besides. It doesn't matter how cheap your heat source is if you need to pay for operating a steam turbine to get any power out. Solar and wind provide high-grade energy directly, so are impossible to compete with anywhere they work.
There are uses for direct heat piped underground to heat buildings, but you don't need to bore to 10km, or even 3km, to get enough heat for that.
