By not abandoning his men at Singapore (as the person directly above him on the list did). He didn't really commit any remarkable feat of courage, I was just alluding to the fact that (unlike the two above him) he didn't commit any egregious act of cowardice.
And that's a big part of how I chose the rankings for my list. Others may have made stupider or costlier mistakes, but if one's actions would have warranted an execution then that person automatically goes to the top of the list.
Yes, and? I'm not considering pre-WWII service (unless it directly impacts WWII performance, as McNaughton's stint as Chief of staff did).