James talks about the royal law and there seems to be no kingdom attached to that law. He is talking about the Sinai Covenant. Loving as I love myself is a nebulous and low profile pursuit. It has become an idol if we think it meets God’s design.
This is my commandment, that you love one another as I have loved you. Greater love has no one than this, that someone lay down his life for his friends. John 15:12-13