STRM, I think you are also right that being calloused would interfere with empathy. I don't see how one could have the patience and strength to be a good therapist day in and day out unless you were motivated by empathy.
The reason my T told me about the client's SU was because I first inquired whether that client would be going on an upcoming group therapy outing. She is a client I have met before on another group outing, and which I happen to have immature feelings of competitiveness and being possessive/territorial over T. It was really bad timing for me to be feeling jealous of her.