Shrieky doesn't doubt the veracity of the advice he's being given. It is almost certainly true that he shouldn't go to Mafaton at night, as would be true of any location filled with creatures that needed to eat something which he contained in order to survive. However... while it's true that he's heard of vampires, he's certainly never met any, and the idea of them congregating in a specific area is intriguing to him.

Maybe he'll just go there during the day.

What she tells him about the riots is... not surprising, exactly, but baffling, "Why would they do that?" He pauses for a moment, before adding, "I mean, I know that they are terrible and perhaps that they don't need any more of a reason than that, but... wouldn't starving, rioting vampires kill many humans?"