God subjected all things in heaven and earth to a created man and that is why all creation must bow down to him. All must bow down to God's throne and His authority and His appointed authority is a man named Jesus. God subjected all things to this risen man when Jesus sat down on his God and Father's throne and all must therefore bow down to the throne of God where this created and exalted man sits. Angels must bow down to this created man because this created has become superior to them because God subjected them to him when he gave the man Jesus all authority in heaven and on earth.

When he had made purification of sins, he sat down at the right hand of the Majesty on High having become as much superior to the angels, as he has inherited a more excellent name than them. Hebrews 1:3-4

....through the resurrection of Jesus Christ who is at the right hand of God, having gone into heaven, angels and authorities and powers having been subjected to him. 1 Peter 3:21-22