For me the question is (and perhaps it is exactly the OP),....
Is the presence of sin (evil) intentional or is it a necessary property of the created?
Although I did post something, thinking out loud, along the lines of evil arising as a consequence or necessary property I think we need to recognize a few things considering that God's attributes cannot be impeached by his action.
If the presence of evil was unintentional that suggests an impeachment of the omniscience and omnipotence of God. We must believe that God knew of sin in eternity and that he had the power to create a world whereby sin was impossible otherwise omnipotence and omniscience are made void. So we must understand the presence of evil as part of the wisdom of God's plan. The important point with respect to God's holiness is that he did not work that evil he only planned to and willed to permit it. I think if this plan was to leave sin in its present state unjudged then his holiness is impeached, but because his eternal decree includes the judging of that evil he remains both holy and just.
I think the point we must confront is that planning to allow sin for his eternal purpose is not a violation of his holiness. He cannot work that evil because he is a holy God, but he can permit it and will and even work the conditions whereby evil arises and this does not besmirch his holiness because all those workings despite some of their (temporary) consequences are good.
It is vital that the presence of evil be not seen as an unintended consequence of creation but as an intended one. And since it is a consequence in the fullness of his omniscience and omnipotence it is by design, but not by active working.
If you ask how is intending evil compatible with God's holiness I think the answer lies in his plan to actively judge that evil. In an eternal God there is no uncertainty or incompleteness so with God, the presence of evil is coupled certainly and completely with its judgement.