I've been reading the web site. I'm guessing that they are going to claim the thing wire is safe because all the circuits have a GFCI on them and the layout of the wires is probably Hot-Ground-Neutral, so you cannot but a nail or screw into them without causing a ground fault and cutting off the circuit.
The things to consider are stables that could easily cause a high resistance short between hot and neutral. It would also be possible to drive one nail into the hot and one into the neutral when hanging a picture. Another good way to get a high resistance short.
I don't see how this flat wire can be safe unless the plastic coating is bullet proof.
