In Luke 15:7 the Lord makes a peculiar statement about repentance,
"I say unto you, that likewise joy shall be in heaven over one sinner that repenteth, more than over ninety and nine just persons, which need no repentance."
Were there really "just" people who "need no repentance"? Your author contends "Yes, there were." If you take the passage at face value, that is the only fitting conclusion.
There is a similar statement made in Luke 5:32 (also Matt 9:13; Luke 15:7),
"for I am not come to call the righteous, but sinners to repentance.
Were there "just" and "righteous" people at the time who the Lord was not calling to repent? That's what the passages say. Most commentators treat these passages a quasi-sarcastic statements by the Lord since all men are sinners. They insist the Lord is saying in a back-handed way He can only call people to repentance who recognize their need. Or in other words those who see themselves as "righteous" are merely self-righteous and won't acknowledge they are sinners who need to repent. That can be a valid application in many cases, especially today. However, when this was spoken there WERE just and righteous people in Israel in the Old Testament sense. Zacharias and Elisabeth were two of them (Luke 1:6), Simeon was another (Luke 2:25), and Joseph of Arimathaea even another (Luke 23:50)
Although it is not explicitly stated, Mary and Joseph were certainly also righteous, else the Lord would not have picked them and sent the angel to converse with them. Could Zacharias, Elisabeth, Joseph, Mary, Simeon, Joseph, and a host of other righteous Israelites be exempt from the Lord's call to repentance? Absolutely. How? Because they had already repented sometime in the past! They don't need to repent again because they remain in a repentant, "blameless" and "just" state. All they needed to do was wait on the Lord and enter His kingdom when it is provided.
Notice in Luke 2:25 how Simeon was "just and devout, waiting for the consolation of Israel: and the Holy Ghost was upon him." He didn't need to repent; he already had years earlier. The proof was the Holy Spirit was upon him while he waited for the Christ. To him and all the other Israelites who were waiting on the Lord, John the Baptist's message of repentance was like "preaching to the choir."
There may still be rare cases in remote locations of people like Cornelius who have repented and seek the Lord the best they know how but are not yet saved because they have not yet heard the gospel, but for the vast majority today the call of the Lord to repent and believe come at the same time with the gospel, He calls "all men everywhere to repent" (Act 17:30) and believe (Act 20:21).