Oborne invokes the dubious “responsibility to protect” standard that retroactively justified the intervention in Kosovo to stop (non-existent) genocide, but beyond compromising the principle of state sovereignty it asserts a new sort of sovereignty of the protector over those whom he protects.
It's the 'non-existent' that got me. Take a historical example, say the Rwandan genocide of 1994, and the subsequent refugee crises. Stipulate that this was a morally undesirable event, and the sort about which we should be concerned. Stipulate further than the recent history of the area was known, including the rise of the Hutu Power movement and the official propaganda directed against Tutsis, as well as the history of violence against the Tutsi. If aware of this, as General Dallaire was, and in the position to stop it, what would be the best time to do so? Certainly somewhere before 800,000 are killed. How much sooner? It's not straining credulity too much to say that if it could be stopped even before it started, that would be ideal; but the sooner the better.
What exactly does that world look like? If the genocide had been stopped at 500 or 5000, no doubt Hutu Power could claim that there never was any intention for widespread violence (in much the same way that no one took responsibility for committing the genocide after it happened, despite the level of organization needed to make it occur, the testimony of eyewitnesses, etc). In a world where the responsibility to protect is taken seriously, and used every time needed, there would be few, or no, genocides, but that would not constitute evidence the standard wasn't useful.