Board Thread:Speculation House/@comment-25316824-20160917214234/@comment-4010415-20160918011505

The Vytal Festival is seen as a celebration of peace and unity among the kingdoms, and Ozpin didn't want regular civilians to be able to suspect that there could possibly be any reason to be worried about their safety or any attacks, hence why Ozpin, Glynda, and Qrow were annoyed that Ironwood brought part of his army to Vale. So, while Ozpin's group was aware that an attack could happen, they didn't want the civilians to be able to figure that out. Paranoia would draw the Grimm.

It's entirely possible that most people wouldn't think that anyone would have the audacity to attack a festival that's all about peace and unity. We, however, live in a world where we wouldn't put it past other humans to perform some kind of vicious attack regardless of the occasion. We live in a world where the worst monsters in existence are other people, while they live in a world where the worst monsters (as far as they're aware) are Grimm.