Health:
It is not absurd at all. Actually, there is abundant discussion in the early literature in psychoanalysis that the connections that develop between a client and therapist can be quite intense, and border on the romantic. It is the responsibility of the therapist to insure that these feelings are kept in check, and only permitted to continue so that the necessary therapy can work. Once the underlying issues have been resolved, this “transference” experience must be resolved to allow the client to achieve full emotional independence. Likewise, the therapist experiences feelings toward the client, called “counter-transference”. The therapist must also be very conscious of these feelings so that they do not move the therapist beyond appropriate boundaries. While psychoanalysis is almost obsolete as a therapeutic modality, many of the concepts are universally recognized as relevant regardless of the therapeutic approach.
If there are emotions that occur, additional steps must be taken to insure that boundaries are not compromised or challenged.
Let’s address halacha. Yichud is assur. That is halacha psukah. No one can challenge that, and excuses are irrelevant. The questions are how to guarantee that a therapy encounter keeps within halachic guidelines. One can safely avoid opposite gender client-therapist situations. But reality is that it is almost unavoidable, and there must be measures taken to prevent yichud – which is assur. Open doors, having arranged for someone to enter unannounced, etc.
Now let’s take another angle for those less inclined to recognize hilchos yichud. Play therapist. You see a client of the oposite gender. One day, after a session where the client was unhappy with the outcome of a session, he or she makes an accusation that you engaged in physical contact, and that he or she was abused by that. Your professionalism, your license, and your career are now on the line. Add to that the possibility of court action with legal costs (almost never covered by any form of insurance including malpractice insurance). Your working life is over. Yes, over. If you would have insured that hilchos yichud were upheld, the accusation would have little chance of being made or sticking, as it would not be believable. So for practical reasons, not just following halacha, yichud laws are critical.