NB
Mate, I've been out of it for a while, but me and my colleagues were, in Paul Keating terms, "done" for much much less.
Look, if the C25A hesitated when he said he would go, this is s**t bad luck for the controller. He used his judgement and from that moment on, LOSA goes out the window.
But in my mind, two aircraft aren't going to get much closer than this. The poor enroute people have to justify 900' and 4.5nm for goodness sake.
I have no axe to grind, but this clerical approach to operational matters leaves me cold.