I'm really getting into it, aren't I? lol
Well, the most obvious reason that God didn't choose to have David be persecuted by his enemies was stated by David himself. He asked not to fall on the hands of humans because they wouldn't be as merciful as God is. So, if David were to have been persecuted by his enemies as his punishment, then he could've died. And what do you think would've happened if David had died? God's promise of a Messiah wouldn't have been fulfilled in him.
justahuman - but super nonetheless