The mention of Moses is meant to emphasize two things. The people want to make sure that their worship of God is in continuity with the past, and the people want to make sure their worship of God is in keeping with what God has commanded.1 The people are eager to do everything exactly as God has commanded them. They are serious about keeping God’s law.
2 Then arose Jeshua the son of Jozadak, with his fellow priests, and Zerubbabel the son of Shealtiel with his kinsmen, and they built the altar of the God of Israel, to offer burnt offerings on it, as it is written in the Law of Moses the man of God.