MJ:
Besides the romex situation, what kind of box is the installer proposing???
From your post, I assume that furring strips aregoing to be fastened to the block wall, and sheetrock will be attached to the furring strips. You cannot staple/strap the RX to the furring strip sides, as you cannot maintain 1 1/4" of clearance to prevent nail damage. 1/2" EMT would work, but you have to install a box.
John


John