You probably knew this, but "act of God" is just a general term for natural disasters that are outside of our power to prevent or control, such as earthquakes or floods. It's just covering their own asses in case a disaster manages to strike in just the right area and ends up shutting down the POL service.
I also think that particular clause already was in their terms of use previously, for anyone that actually bothered to skim through it before (hah)