“…the panel was plainly looking for a risk management plan which would manage the Applicant’s risk indefinitely: it was looking for a whole range of provision for him, as recommended by the psychologists and the COM. One essential component was a period in [designated accommodation] followed by appropriate moving-on accommodation. The panel was entitled to find that the short period in [designated accommodation], which was all that could be found, was not sufficient; and it was entitled to derive support for this view from the psychological witnesses”