Of course Nitai is Gunamani! The one who is completely Guna-grahi (accepts only one's good qualities) and cent percent adosha darashi must be a reservoir of good qualities only! Nitai is extraordinary especially because of this jewel-like quality which only He possesses! Where will you find another personality with this quality?
Nitai is Gaur Guna Dham, the abode and repository of all of Gauranga's astonishing qualities! This is attested to by Advaita Acharya Himself. The one who carries all of Gaur Krishna's magnificent qualities and at the same possesses His own unique qualities of servitorship and devotion to the Lord must be GUNAMANI - the one and only jewel-like personality!
Nitai is Gunamani, that means His qualities are so great that they overpower our own insurmountable demerits. He can deliver us by the power of His own qualities without having to depend on our own qualifications at all.