That would be a handy way to do a keypad for radio use.

I have a project in build at the moment which strobes the keypad lines, unfortunately this generates interference in the receiver.
Using decoupler caps prevents the strobe. Using ferrite bead chokes reduces the output of each line.

I'm using a 4x3 keypad as it suits my needs.

With precision resistors this could be a good way to do it once the ADC values have beeen determined for each keypress.

Rob