Patrick, I don't know, as Z. usually has the right to appoint. Maybe not in this case. See below. (From Daily Maverick - Pierre de Vos)
Usually the president has the discretion under section 84(2)(f) of the Constitution to appoint commissions of inquiry. The remedial action now fetters this discretion. The question a court will have to answer is whether the special circumstances of this case render this fettering of the president’s constitutional powers constitutionally valid or not. Is it permissible – in these extraordinary circumstances in which the president is being implicated in breaches of the Ethics Act and in possible corruption – for the Public Protector to restrict the constitutional powers of the President?
The problem faced in this case is that there are excellent reasons why the president should not have the discretion to appoint a judge of his choice to head a commission of inquiry to investigate matters delineated by the president. The president is conflicted as he is implicated in wrongdoing which would have to be investigated by the commission of inquiry. It is inevitable that if his discretion is not fettered he would appoint a judge he perceived to be sympathetic to him. This conflict of interest would almost certainly invalidate the entire commission.