What does Acts 23:18 mean?

Paul, as a Jew, was circumcised as an infant (Philippians 3:5), raised in Jerusalem, and trained by the famous Pharisee rabbi Gamaliel (Acts 22:3). He had so much passion for the Mosaic law that he voluntarily hunted Jesus-followers for the Sanhedrin (Acts 8:1–3; 9:1–2), voting against the Jesus-followers if they did not abandon their faith (Acts 26:10).

Once he met Jesus on the road to Damascus, Paul's relationship with the Jewish leadership changed to the point that now the Sanhedrin is conspiring to assassinate him (Acts 23:12–15). In fact, Paul has a better relationship with the Roman military than his former colleagues. The tribune of Jerusalem has already rescued him from the Jews twice (Acts 21:31–32; 23:10) and is about to do so again. One of the centurions posted in Jerusalem had the presence of mind to keep Paul from being flogged (Acts 22:22–29) and another will protect him from being killed during a shipwreck (Acts 27:42–43).

So, when Paul's nephew hears of the Sanhedrin's murderous plot, Paul trusts the centurion will take the information to the tribune (Acts 23:12–17). The tribune will validate Paul's trust, sending him with an escort of two centurions, two hundred soldiers, seventy horsemen, and two hundred spearmen to the relative safety of the governor in Caesarea Maritima (Acts 23:23–24).