This seems like scummy reasoning to me:
Now, the Townies would be wise not to put too much faith in Red Skeezix’s false claim, because he was definitely lying about his own role and could easily have invented the Fenrir role himself. Or maybe there is a vanilla Scum player whose character name happens to be Fenrir, in which case it really doesn’t matter that Red Skeezix decided to use the same name. But given the number of special roles we’ve seen already, I don’t find it implausible that there is a Scum Fenrir character who is NOT substantially different from the role described by Red Skeezix. I wouldn’t bet the farm on it, but I see no reason to assume that there couldn’t be a Scum character with the power to perform an extra night kill.
I don’t know what Chronos’s motives are for dismissing Ninja’s concerns if he is Scum, though – it may be that she was on the right track and he wants to mislead the Town, or it may be that he knows perfectly well there’s no special Fenrir role and is either trying to act pro-Town by preventing the others from wasting time or that he’d just find it annoying to read and play along with a bunch of debate about a topic he knows is fruitless.