My understanding is they propose to excite the material with electromagnetic waves until it undergoes a phase shift, solid to liquid to gas. So then they have

My understanding is they propose to excite the material with electromagnetic waves until it undergoes a phase shift, solid to liquid to gas. So then they have superheated gaseous rock in the bottom of the bore hole, how do they get it out? Conservation of mass: it must go somewhere. Ventilation isn't so simple. The gaseous rock will condense, then harden on the walls of the ventilation tube. Or, maybe it reacts with the materials of your down-hole equipment.