Shimei said God had given David’s kingdom into the hands of his son Absalom. And David said the things Shimei was saying against him were what God had told him to say. So this statement in favor of Absalom being king seems to be coming from God.

But in the chapter after that, the Bible says God influenced Absalom to listen to bad advice, in order to bring disaster on Absalom. So God doesn’t seem to be in favor of Absalom being king.