As an atc unit, we have the facility to moniter and transmit on 121.5, but I would be reluctant to answer a transmission on the frequency unless:
1) I knew that the station was unable to establish 2 way contact with D & D or an airborne/surface rescue unit, or,
2) I had been asked to act as an intermediatory.
I would suggest that the same applies to pilots.
Good intentions often lead to unnecessary confusion!
