For a little clarification, since I've actually been involved in processes like this, it's not the airline that charges for the delivery, it's the delivery company that they contract to... Now, in cases where it's the airline's fault, they pay the delivery charge. If it's a case of late check-in or some other situation where the airline is not at fault, the passenger has to either pick up the bag or pay for the delivery. The drivers at most of these delivery companies use their own vehicles and get paid a percentage of the delivery charge, and pay for their own gas, then take that out of their taxes... It used to be a really great deal, but gas prices have made it pretty poor now too.
I don't know the situation with this particular deliver, obviously, but it could be that it was a bad day for the agent and they either believed (or possibly knew) that it was a case where CO
wasn't liable for the delivery. Or, on the other hand, someone could have blown an innocent comment out of proportion... lord knows, THAT's NEVER happened.
Make something Idiot-proof, and the Universe will make a more inept idiot.