Because Krsna had caught the demon's neck, the demon (Trnavarta) was unable to throw Him off. He therefore thought of the child as wonderful, since he could neither bear the child nor cast aside the burden - SB 10.7.27

Expressions researched:
"because Kṛṣṇa had caught the demon's neck, the demon was unable to throw Him off. He therefore thought of the child as wonderful, since he could neither bear the child nor cast aside the burden"

Srimad-Bhagavatam

SB Canto 10.1 to 10.13

Because of Kṛṣṇa's weight, Tṛṇāvarta considered Him to be like a great mountain or a hunk of iron. But because Kṛṣṇa had caught the demon's neck, the demon was unable to throw Him off. He therefore thought of the child as wonderful, since he could neither bear the child nor cast aside the burden.

SB 10.7.27, Translation and Purport

Because of Kṛṣṇa's weight, Tṛṇāvarta considered Him to be like a great mountain or a hunk of iron. But because Kṛṣṇa had caught the demon's neck, the demon was unable to throw Him off. He therefore thought of the child as wonderful, since he could neither bear the child nor cast aside the burden.

Tṛṇāvarta intended to take Kṛṣṇa up in the sky and kill Him, but Kṛṣṇa enjoyed the pastime of riding on Tṛṇāvarta's body and traveling for a while in the sky. Thus Tṛṇāvarta's attempt to kill Kṛṣṇa failed, while Kṛṣṇa, ānanda-cinmaya-rasa-vigraha, enjoyed this pastime. Now, since Tṛṇāvarta was falling because of Kṛṣṇa's heaviness, he wanted to save himself by throwing Kṛṣṇa off from his neck, but was unable to do so because Kṛṣṇa held him very tightly. Consequently, this would be the last time for Tṛṇāvarta's yogic power. Now he was going to die by the arrangement of Kṛṣṇa.