He did it because He knew revealing Himself could lead some to believe and He did not want them to come to repentance yet (not until after He is crucified and raised up does He draw all men to Himself, Jn. 12:32). This demonstrates that Jesus knew the truth was more than sufficient to draw the lost to repentance. He had a bigger redemptive purpose to accomplish through them first, so He “judicially hardened” them from seeing the otherwise enabling truth of God’s Word.