He sees that they need him, and that his presence is going to be a reminder, so he works with them. Not just that, but he makes Aaron, the person who was the one who built the calf and sacrificed to it. He makes him the high priest of his tabernacle. And this in itself is an amazing image of Jesus, and that God came down to earth to dwell with his people, to show them the way to life, and to give them the opportunity to live in harmony with God by obeying and following Jesus' law.