According to normal standards,
All of Bo Man's family members should have been arrested and brought to justice.
But the world isn't black and white; there's also a gray area in between.
Justice and evil have different boundaries in the eyes of different people. For example, the President of the US who started a war with a single word and caused the deaths of so many should have been judged by justice long ago.
Unfortunately, he was not.
He still lives well, carefree and at ease.
Waite saw it the same way.
Despite the many crimes committed by Bo Man's family, some of which were truly vile and deserving of death by law, in Waite's balance, there were not only just and evil but also pros and cons.
Letting them go avoided a war.
The outcome was a win for Waite.
The most important thing was,
Black Prison said it would ensure that those people would not come back for revenge.