They were from the same land as the Red Blood Palace. There never had been any serious feud or animosity between the two great factions, and the two could be considered allies.
Even if they did sign the Book of the Heart's Oaths, the Red Blood Palace was unlikely to slaughter them intentionally. But they would lose all respect for them!
However, it would also be a great pity if the students of the Purple Cloud Palace had to give up the chance to enter the martial tower.
The martial tower was a place with an abundance of opportunities and rewards for the challengers. It had always been that way, and they would badly regret it if they simply gave up on it.
As they weighed up the odds, many of the students of Purple Cloud Palace were remorseful. If only they had stood up for the Red Blood Palace when they were being bullied by the Heavenly Knife Region earlier, they wouldn't be in such a predicament right now.