The idea is that generally the liberated souls are attached to the feature of impersonal Brahman with a monistic view of becoming one with the supreme whole. But by the association of pure devotees like Vyāsadeva, even the liberated soul becomes attracted to the transcendental qualities of the Lord. By the mercy of Śrī Nārada, Śrīla Vyāsadeva was able to narrate the great epic of Śrīmad-Bhāgavatam, and by the mercy of Vyāsadeva, Śrīla Śukadeva Gosvāmī was able to grasp the import. The transcendental qualities of the Lord are so attractive that Śrīla Śukadeva Gosvāmī became detached from being completely absorbed in impersonal Brahman and positively took up the personal activity of the Lord.
Practically he was thrown from the impersonal conception of the Absolute, thinking within himself that he had simply wasted so much time in devoting himself to the impersonal feature of the Supreme, or in other words, he realized more transcendental bliss with the personal feature than the impersonal. And from that time, not only did he himself become very dear to the viṣṇu-janas, or the devotees of the Lord, but also the viṣṇu-janas became very dear to him. The devotees of the Lord, who do not wish to kill the individuality of the living entities and who desire to become personal servitors of the Lord, do not very much like the impersonalists, and similarly the impersonalists, who desire to become one with the Supreme, are unable to evaluate the devotees of the Lord. Thus from time immemorial these two transcendental pilgrims have sometimes been competitors. In other words, each of them likes to keep separate from the other because of the ultimate personal and impersonal realizations. Therefore it appears that Śrīla Śukadeva Gosvāmī also had no liking for the devotees. But since he himself became a saturated devotee, he desired always the transcendental association of the viṣṇu-janas, and the viṣṇu-janas also liked his association, since he became a personal Bhāgavata. Thus both the son and the father were completely cognizant of transcendental knowledge in Brahman, and afterwards both of them became absorbed in the personal features of the Supreme Lord. The question as to how Śukadeva Gosvāmī was attracted by the narration of the Bhāgavatam is thus completely answered by this śloka.