Could The Ex-Gay Ban Backfire?

Christopher Ferguson fears that banning ex-gay therapy for minors, as California has done, "may simply drive it underground, where it won’t even be subject to state regulation or limited to therapists who are licensed." Also:

There are a number of therapies out there which have been empirically demonstrated to range from useless to outright harmful. Scott Lilienfeld, a professor of psychology at Emory University, discussed this in a 2007 issue of Perspectives on Psychological Science. Among the therapies he looked at were questionable ones such as facilitated communication, “rebirthing” therapies, and “recovered memory” therapy. But they also included relatively popular approaches such as “Scare Straight” for kids who are at risk for delinquency, boot camps kids who are anti-social, and DARE anti-drug programs. If we are going to start down the road of banning therapies, should we not ban these all, if the research evidence continues to bear out Dr. Lilienfeld’s concerns?  Why do we ban gay conversion therapy but leave DARE programs intact?