It shows the second sending. I took a look back in the thread. You wanted to know what "shows us this was much later than his initially being sent". It screams different! Look at verse 17 in Acts 22. That is not what happened in Acts 9. Paul (then Saul) was not in the temple praying and in a trance when the risen, ascended Lord Jesus Christ first appeared to him in Acts 9. Was he?
Acts 22:17 And it came to pass, that, when I was come again to Jerusalem, even while I prayed in the temple, I was in a trance;
Of course not. Saul was here in Acts 9 at the first appearing:
Acts 9:1 And Saul, yet breathing out threatenings and slaughter against the disciples of the Lord, went unto the high priest,
Acts 9:2 And desired of him letters to Damascus to the synagogues, that if he found any of this way, whether they were men or women, he might bring them bound unto Jerusalem.
Acts 9:3 And as he journeyed, he came near Damascus: and suddenly there shined round about him a light from heaven:
Luke's account in Acts 26 about the Acts 9 encounter gives us much detail. Pay close attention to the language in the King James Bible. There is not only one appearing and sending, but the promise of a future appearing and instructions. There is a specific audience and an immediate sending in Acts 9..." unto whom now I send thee". Watch the tenses.
Acts 26:13 At midday, O king, I saw in the way a light from heaven, above the brightness of the sun, shining round about me and them which journeyed with me.
Acts 26:14 And when we were all fallen to the earth, I heard a voice speaking unto me, and saying in the Hebrew tongue, Saul, Saul, why persecutest thou me? it is hard for thee to kick against the pricks.
Acts 26:15 And I said, Who art thou, Lord? And he said, I am Jesus whom thou persecutest.
Acts 26:16 But rise, and stand upon thy feet: for I have appeared unto thee for this purpose, to make thee a minister and a witness both of these things which thou hast seen, and of those things in the which I will appear unto thee;
Acts 26:17 Delivering thee from the people, and from the Gentiles, unto whom now I send thee,
The sending in Acts 22 is different. "Now send thee" is not the same as "will send thee". The tenses are different, not to mention that I believe the Gentiles to whom Paul was making known that he was going to be sent in Acts 22, were different.
Acts 22:21 And he said unto me, Depart: for I will send thee far hence unto the Gentiles.
Acts 22:22 And they gave him audience unto this word, and then lifted up their voices, and said, Away with such a fellow from the earth: for it is not fit that he should live.
Acts 22:23 And as they cried out, and cast off their clothes, and threw dust into the air,
Acts 22:24 The chief captain commanded him to be brought into the castle, and bade that he should be examined by scourging; that he might know wherefore they cried so against him.
That is the "cause" that Paul was a "prisoner of Jesus Christ for you Gentiles" (Ephesians 2:11-12 KJV, Ephesians 3:1 KJV).