‘And they knelt down before him, and mocked him, saying, “Hail, King of the Jews!” '
But central to it all was the desire to mock His ‘claim' to Kingship, and the horseplay no doubt began early and continued right through to the end as different ones thrust themselves forward trying to outdo what the previous ones had done. It is summarised here in the terms ‘they knelt down before him, and mocked him, saying, “Hail, King of the Jews!” ' They knew after all that that was what lay behind His sentence. It was the accusation that the Chief Priests and Elders had felt was most suitable to present before Pilate, and that Pilate had brought before Jesus. It will also be paraded on His cross in order deliberately to anger the Jewish leaders. For this was how Gentiles saw the Jewish Messiah.
Note the contrast with the treatment by the Jewish guards (Matthew 26:68). They had mocked Him as a prophet and Messianic pretender, these mocked Him as a failed claimant to Kingship. It all rings true.