John 9:19-23 - He is of age

9:19,20

The religious leaders had considerable power in society, they could throw someone out of the synagogue which would make life difficult for them. This is the reason for the parent’s wariness. So when the Pharisees ask how their son could now see if he had been born blind, they simply reaffirm what they had said. The man was their son and had been born blind.

9:21

They could not get into trouble for what they had already said, they were simply stating facts. However, they decline to offer an opinion as to how he could now see. Instead they refer the Pharisees to their son. This was actually quite reasonable, for they had not been there at the healing, so their son was the first hand witness. The son was of age, so his testimony was legally valid.

9:22,23

John gives an explanation of the reluctance of the parents to say too much. The religious leaders (“the Jews”) had agreed that anyone speaking well of Jesus would be evicted from the synagogue. This is the reason the parents told the Pharisees to ask their son directly.