During the time that Snow was calmly walking to the clearing, a group of people wearing professional clothes when dealing with a person being contaminated by a vile aura has started to surround him.
Depending on how an individual is affected by the vile aura, there is a level of effect when being infected, while turning into a Fallen is the last one among the list of being contaminated.
And a person can still be saved even when being affected by the vile aura.
It was also the reason why Samuel has been able to calmly speak toward them the whole time without any apprehension, especially when Snow wasn't showing the status of a person in the way of becoming a Fallen.
In Ange and Brian's understanding, Snow that wasn't crazy, or losing his mind and acting out in a destructive manner is evidence enough that his status is completely unusual, especially when Ange and Brian already have the cognition that he has already turned into a Fallen.