Has the author lost the plot?

Harry Potter and the Deathly Hallows

Unfortunately, the brilliance that Bathilda exhibited earlier in her life has now dimmed. ‘The fire’s lit, but the cauldron’s empty,’ as Ivor Dillonsby put it to me, or, in Enid Smeek’s slightly earthier phrase, ‘She’s nutty as squirrel poo.’

Rita Skeeter