The point of getting medical training is to practice medicine.
Psychologists should not be doing this.
Basically he's describing someone who goes to psychology school, gets trained as a psychologist, then takes cursory coursework, presumably with no clinical rotations with resident responsibilities (where "real" medicine is learned) then somehow applies this to psychiatric patients.
Seriously, if someone is so interested in mental health, medicine, and psychopharmacology, get your MD or DO and play all you want. That's what it is. Why do we have to invent some complicated, artificial degree program?
The extrapolation of this to other medical fields sounds even more ludicrous. Why not let the CCU nurse take medical courses, pharmacology training, and see cardiac patients? The standard of care in that scenario is to just see a friggin' cardiologist. The route for this type of education is already in place.
There is no Master's in medicine that I'm aware of that carries any kind of serious clout. This doesn't really seem to be a realistic question.
If all you want is medical training and/or knowledge for your personal interest...be my guest. But the minute you start applying or making medical recommendations - that's a serious problem for both you and the patient.