i suspect many Ts who may be understanding to and in support of psychedelics won't openly discuss or encourage the use of psychedelics to their clients, unless the client brings the topic up first or unless they advertise specifically as an integration therapist. MAPS does provide a list of integration therapist on their site:
Psychedelic Integration List - MAPS

there are some very positive research results currently being released in regards to the use of psychedelic/mdma assisted therapy for helping with PTSD and depression and there are many therapist who believe in, and have witnessed, the powerful potential of these healing substances (my ex-T is one of them and he currently is seeking training and approval to do this kind of therapy in my country). many therapist who may be interested in working with the healing potential of psychedelics, but want to keep their noses clean, will offer to help with integration sessions (the client does the psychedelics in their own setting and meets with the T for regular sessions afterwards to help process and integrate the experience). the therapists who are administering any drugs are either involved in clinical studies with clients (which have been approved) or there are some underground Ts willing to help. it's those underground Ts who provide access to illicit drugs who will carry the greatest risk to getting into trouble when it comes to doing this kind of therapy. but for whatever reason, some chose to do this and take that risk.

i personally feel that the main area where this may become, as you said, 'trouble waiting to happen' will be after mdma/psychedelic assisted therapy is approved by the FDA and available in clinics for clients. i don't fear that the influx in the use of this medicine for those who are suffering will be the issue, i fear it will be the influx of psychologists wanting to become trained in the 'latest and greatest' to be part of the fashionable trend of the newest therapeutic modality, and that they won't fully achieve the proper competency needed too do this kind of delicate work. and similar to normal psychotherapy, if these therapist don't have their s*#t together, their issues sorted, etc, then i fear there is even a greater potential to client harm due to the increase in vulnerability that these substances will cause.