QRTZ should actually generate SPRK when under pressure. It is a piezo-electric crystal which means it creates a voltage from pressure. It isn't a piezo-conductive material (if there is such a thing), which would mean it would conduct under pressure.
Pretty sure QRTZ says it conducts in its element description. It conducts from direct touch with metal under -100 C, and conducts above about 7~ ish pressure.
But yeah, since you need a high-pressure environment to get it to spark in the first place in this condition, we didn't put much thought into making a failsafe for spark looping. :P