What does Luke 23:20 mean?

Jewish religious leaders have cornered the Roman governor, Pilate, in a political dilemma. Along with a mob, Jerusalem's leadership brought Jesus whom they claimed was calling Himself king and disturbing the Jews from Judea to Galilee. Pilate questioned Jesus and found Him innocent. But no matter what he does, the crowd refuses to accept his verdict (Luke 23:1–5, 13–19).

Pilate wants to release Jesus for several reasons. First, of course, He's innocent, and Pilate has no desire to do someone else's dirty work. Second, even Herod Antipas agrees that Jesus doesn't deserve death (Luke 23:15). Third, Pilate's wife has had a dream; she wants him to "have nothing to do with that righteous man" (Matthew 27:19). Pilate is a high-ranking Roman soldier. He knows the Jewish leadership is jealous of Jesus' popularity (Matthew 27:18). But he can't figure out how to cut through their pride so they will accept the truth.

Now, the throng of protestors insist Pilate release Barabbas, not Jesus, for a traditional Passover pardon. Barabbas is an insurrectionist and a murderer (Luke 23:18–19). He's been proven to be more of a criminal than they've claimed Jesus is.

Luke's narrative puts the responsibility for Jesus' death firmly on the leaders and the people, but Pilate is not upheld as innocent. He "desires" to release Jesus, yet he could easily use his power as governor to do so. Ancient history suggests that Rome had warned Pilate about his overly violent responses to Jewish unrest. He may have been concerned that defying the mob would spark the very insurrection Jewish leaders claimed they're trying to avoid.