He was being blunt to those who refused salvation because they were so caught up in their own rightness they had become fools.
He wasn't nit picking or just being mean. He wasn't arguing just for the sake of an argument.
The Bible itself is clear on such things.
It is one thing to have a frank discussion another to argue and bicker.
Act 9:29 And he spake boldly in the name of the Lord Jesus, and
disputed against the Grecians: but they went about to slay him.
Act 17:17 Therefore
disputed he in the synagogue with the Jews, and with the devout persons, and in the market daily with them that met with him.
Acts 19:8 And he went into the synagogue, and spake boldly for the space of three months,
disputing and persuading the things concerning the kingdom of God.
Acts 19:9 But when divers were hardened, and believed not, but spake evil of that way before the multitude, he departed from them, and separated the disciples,
disputing daily in the school of one Tyrannus.
Titus 1:10 For there are many unruly and vain talkers and deceivers, specially they of the circumcision: 11
Whose mouths must be stopped, who subvert whole houses, teaching things which they ought not, for filthy lucre's sake. 12One of themselves, even a prophet of their own, said, The Cretians are alway liars, evil beasts, slow bellies. 13This witness is true. Wherefore
rebuke them sharply, that they may be sound in the faith;
Gal 2:11 But when Peter was come to Antioch, I
withstood him to the face, because he was to be blamed.
Jud 1:3 Beloved, when I gave all diligence to write unto you of the common salvation, it was needful for me to write unto you, and exhort [you] that ye should
earnestly contend for the faith which was once delivered unto the saints.