这句 he still does not know enough to come in, out of the rain

这句 he still does not know enough to come in, out of the rain 啥意思呢?
句子在下边最后一段：
We were over the hill before this insane movement could be discovered and stopped. And what did we find? A large and unsuspecting Russian army waiting! And what happened? Were we all killed? That is exactly what would have happened in ninety-nine cases out of a hundred. But no – those surprised Russians thought that no one regiment by itself would come around there at such a time.
"It must be the whole British army, they thought. They turned tail. Away they went over the hill and down into the field in wild disorder, and we after them. In no time, there was the greatest turn-around you ever saw. The allies turned defeat into a sweeping and shining victory.
"The allied commander looked on, his head spinning with wonder, surprise and joy. He sent right off for Scoresby, and put his arms around him and hugged him on the field in front of all the armies.
"Scoresby became famous that day as a great military leader, honored throughout the world. That honor will never disappear while history books last.
"He is just as nice and pleasant as ever, but he still does not know enough to come in, out of the rain. He is the stupidest man in the universe.
全文：
http://www.***.com/VOA_Special_English/American_Stories_27307.html
谢谢大家!