Heavily unsuited!
OR
Ok, that will work except in the case of multiple keys pressed.

You can principally not detect which key is pressed, when the column is high, because then all rows are high at the same time
while I agree that the method is very untraditional, it does work. He detect that an input is low and then he find out how to make it 'not low'. Just like you find which of a number of components in parallel cause a short by removing them one at a time.

Would I use this method? NO, fingers and keys = static and reading a low is so much more solid. That, however does not make Marks logic faulty.

Erik