Why did Stephen's vision of Jesus standing at God's right hand imply that he was ready to return?

Les explains that although believers usually think of Jesus as seated at the right hand of God, the Jew knew that if He was anywhere, He was to be seated. For Him to be standing implied that He was ready to return. The Old Testament spoke of Him sitting at the Father's right hand until His enemies were His footstool, and then one of the Psalms told the nation of Israel that He would arise, that is, stand, and be ready to come and deal with His people. The Jew caught that implication. So when Stephen said he saw Him standing on the right hand of God, the crowd cried out with a loud voice, stopped their ears, ran upon him with one accord, cast him out of the city, and stoned him. The witnesses laid down their clothes at a young man's feet whose name was Saul. Saul was consenting to Stephen's death, and a great persecution followed against the church, which in Greek is ecclesia, a called-out assembly.