Ron just ignored Hermione's question of "Never mind what." If he gave into it they would be arguing in no time. So, instead he tried to steer he conversation more towards talking about Zombies. Ron liked talking about zombies even if it was arguing with Hermione about whether or not they were real.
Of course Hermione had read the newspapers. Why did Ron always think he could give information to this girl that she didn't already have? Wishful thinking. "I still say it's a part of the Zombie Apocalypse," Ron said stubbornly. "Because if it's not that then I don't know what it is."