With proviso: I’m a birder, not disease doc.
I think [not certain, not re-reading paper just now] the mice were injected with vaccine. If such injected mice got into homes, maybe their faeces could carry virus, so if these can enter food, or otherwise perhaps to mouths (children touching surfaces, maybe), maybe virus could enter people – but even then, it’s a poultry flu and we’re not chickens.
That said: after all the poultry infections in China, surely many mice (and rats) have been in vicinity of, sometimes in contact with, infected chickens and their droppings. Yet no records I know of, of wild mice/rats with H5N1.