I don't quite understand why Zahard is inactive, unless.. an option came to mind. Zahard is immortal, for better or worse. But we all know that immortality does not always equal things like eternal youth. Well in tower it does. But I have a theory that Zahard is inactive either because he had a complete mental breakdown or he no longer has a functional human body. I mean, he might be immortal but that doesn't stop someone from severing his legs off and taking them somewhere?

I'm bringing this up, because the incident at Hand of Arlen, the "birth of a new slayer" stuff, declaring "Jyu Viole Grace" etc. It should have been like a parade of red flags accompanied by loudspeakers and sirens to Zahard family. The irregular baby you tried to kill is alive. You know the one whose family you had a war with.

Somebody should have at least checked the rumor. Unless. Uhh. They did? In the very next big arc, workshop battle. http://towerofgod.wikia.com/wiki/Po_Bidau_Gustang

Best theory I can come up with is that Bam is being protected by someone very high up, either one or more people who are obfuscating Bam's existence from Zahard faction.

A random thought. From what is sounds like, Jyu Viole Grace might be a more real name for Bam, than "25th Bam".