Zhou Tian appeared remarkably relaxed while fighting the angels due to his powerful strength. The disparity in strength between Zhou Tian and the angels was great, leaving the angels without any ability to resist.
At that time, the modified angels and the unmodified ones didn't have much difference in strength. Although the unmodified angels attacked the rear of the angelic army, causing some chaos, their actions weren't enough to alter the strength disparity between the two sides.
The angels who arrived had no intention of dealing with the angelic army; their objective was rescuing their 'companions.' As long as they incited chaos and offered their 'companions' an opportunity to escape, their mission was achieved.
Without such a purpose, the angels wouldn't have considered confronting the angelic army due to the vast strength disparity. It wasn't about achieving results but rather escaping without being captured.
