He doesn't have to buy a damsel. Chromis sell for $10. I sure haven't seen any clowns for under $30 each. My suggestion was to go with something inexpensive to start out with since he has already lost a chunk of change and is discouraged.
I understand what you're saying, but I still don't think adding a fish that wasn't on his intended stock list as a canary in a coal mine, so to speak, isn't what I would do.