Because of this.
The context is the time right after Jesus rose from the dead.
JOHN 20:18 Mary Magdalene went to the disciples with the news: "I have seen the Lord!" And she told them that he had said these things to her. JN 20:19 On the evening of that first day of the week, when the disciples were together, with the doors locked for fear of the Jews, Jesus came and stood among them and said, "Peace be with you!" 20 After he said this, he showed them his hands and side. The disciples were overjoyed when they saw the Lord. JN 20:21 Again Jesus said, "Peace be with you! As the Father has sent me, I am sending you." 22 And with that he breathed on them and said, "Receive the Holy Spirit. 23 If you forgive anyone his sins, they are forgiven; if you do not forgive them, they are not forgiven."49 [Jesus said] I am going to send you what my Father has promised; but stay in the city until you have been clothed with power from on high."
ACTS 1:8 But you will receive power when the Holy Spirit comes on you; and you will be my witnesses in Jerusalem, and in all Judea and Samaria, and to the ends of the earth."
ACTS 1:12 Then they returned to Jerusalem from the hill called the Mount of Olives, a Sabbath day's walk from the city. 13 When they arrived, they went upstairs to the room where they were staying. Those present were Peter, John, James and Andrew; Philip and Thomas, Bartholomew and Matthew; James son of Alphaeus and Simon the Zealot, and Judas son of James. 14 They all joined together constantly in prayer, along with the women and Mary the mother of Jesus, and with his brothers.
AC 1:15 In those days Peter stood up among the believers (a group numbering about a hundred and twenty) 16 and said, "Brothers, the Scripture had to be fulfilled which the Holy Spirit spoke long ago through the mouth of David concerning Judas, who served as guide for those who arrested Jesus-- 17 he was one of our number and shared in this ministry."ACTS 2:1 When the day of Pentecost came, they were all together in one place. 2 Suddenly a sound like the blowing of a violent wind came from heaven and filled the whole house where they were sitting. 3 They saw what seemed to be tongues of fire that separated and came to rest on each of them. 4 All of them were filled with the Holy Spirit and began to speak in other tongues as the Spirit enabled them."
From the above verse through the end of Acts Chapter 2, you will see the rest of the dramatic transformation that overcame Peter, who had denied Christ three times before the Cross (before he was indwelt by God's Spirit) but then, filled with the power of the indwelling Holy Spirit, rose up in the midst of a group who'd been hiding for fear of the Jews, stood boldly and proclaimed the gospel to them, and over 3,000 souls were saved that day.
Before the Cross, Jesus said to the disciples, "If you love me, you will obey what I command. And I will ask the Father, and he will give you another Counselor to be with you forever -- the Spirit of truth. The world cannot accept him, because it neither sees him nor knows him. But you know him, for he lives with you and will be in you. I will not leave you as orphans; I will come to you. Before long, the world will not see me anymore, but you will see me. Because I live, you also will live. On that day you will realize that I am in my Father, and you are in me, and I am in you. Whoever has my commands and obeys them, he is the one who loves me. He who loves me will be loved by my Father, and I too will love him and show myself to him." (John 14:15-21)
When Jesus breathed on the disciples they entered into the fulness of their salvation, meaning, they could be no more saved than they were that day. On the day of Pentecost, the Father sent the Holy Spirit again to give the disciples (even more) power to be His witnesses. Hence, we see the 180 degree turn-around in Peter, confirming Jesus' words that "you shall know them by their fruits."
So, what has that got to do with the Jordanian? He may have still been cowering in fear in the upper room, from a spirirual perspective, not yet having his eyes opened.