well.. it seems easy from the instructions right? imagine if u did the scallop on your beloved Fender/Gibson/PRS... and being a first-timer, you accidentally SLIP.
not that i'm slighting your ability to file... but the risk is there. i screw up often during soldering and wiring guitar electronics.. the only good thing is that electronics are often much more easily salvagable.
if you also notice, the writer of the tutorial didn't actually scallop his neck that well also... (last 3rd pic)... you might find yourself in that situation.
like how i put it in my last line - if you have a guitar neck to waste - you might want to start off with a cheap guitar that u wont feel the pain if you should screw up or if u should end up hating scalloped necks.