DaoistZenFeng
He could tell them to question Nifleheim separately and get the same story from him about the Shadahi origin to prove his point. I'm also curious why neither Izroth nor Nifleheim have used the reward legacies they recieved yet.
Izroth must not necessarily have included Nifleheim into his report. We must not forget, that RML is a place, where everyone seeks more power to grow and the strong feast on the weak. The treasure Niflheim obtained can not be regarded as secured. For himself Izroth might be confident to protect, what is his, which he can not for Niflheim. We also don't know if Izroth included the Inheritance keystones into his report. He would endanger Nifleheim and at least create more potential trouble for himself. Further on there seems to be a leak of intelligence. Even though Izroth might trust those present, who might stand by their words, the intelligence network is most certainly corrupted. Let’s also remember the Shadahi corrupted player from the Chaotic Dogma Realm - that was supported by an absolute 'Bigwig'. A figure of such power will be able to see through a beginner level players fassade easily, but allowed a Shadahi collaborationist to not only infiltrate a sensible and important operation but very likely gave the order to kill as many players as possible and lead the mission to fail...