There's a proverb that says that the wicked flee when no man pursues. I hardly think that God would call David a wicked man. He had times when he was far from God. Here, we see a time that he fled for his life (incidentally the bible says that he fled into the wilderness, which is interesting). He went to the wilderness east of Jordan. Now why did this man flee? Wisdom dictated that David was in no position to defend the city. He was outnumbered; he was outgunned. Absalom, in his strategy, had gained the upper hand and so David decided that it was better to have the freedom of movement—in an open place—than it was to be trapped in a city, where he would be subject to a siege.