How to protect against shock from exposed romex?
If you don't have the option to install an alternative handhold, you could protect the cable using conduit.
WARNING: If you're not comfortable with electrical work, please contact a local licensed Electrician.
Supplies

Single gang electrical box, suitable for use with rigid PVC conduit.
A length of PVC conduit (10' of 1/2&quot; should be fine).
A bag of PVC conduit clamps.
Conduit offsets if required
Cable staples

Procedure

Start by turning off the power to this circuit at the breaker, and verifying the power is off using a non-contact voltage tester.
Remove the cover from the electrical box, and remove the screws holding the switch in place.
Gently pull the switch from the box, leaving the wires attached .
Make a detailed sketch (or take a photo) of the existing wiring.
Remove each wire from the switch, labeling each as you go.
Remove any twist-on wire connectors (or other connectors), labeling all separated wires as you go.
Carefully remove any cable staples securing the cables to the 2x4.
Carefully pull the cables from the existing box.
Remove the existing box.
Measure and cut the PVC conduit.
Feed each cable through a length of conduit.
Feed the cables into the electrical box.
Connect the conduit to the box (NOTE: depending on the box, and how it's oriented, you may need offsets).
Install conduit clamps within 18&quot; of the electrical box, and every 3' after that.
Install a cable staple within 12&quot; of where the cable enters the conduit.
Install the switch using your notes, sketches, photos, and labels as a guide.
Install the box cover, and turn the power back on.