The procedure was tested on live animals. I guarantee you that what they describe is precisely what happens. There's no guarantee that it prevents all types of flu, but that is not what the paper claims.

There's further no guarantee that the rat survives, or mates, or becomes emperor of China for that matter. What is reproducible is what is described in the paper, not what you might wish would follow.

Reproducibility is a very specific requirement. It requires that, following the procedure as outlined, you will find similar data. It has nothing to do with application, or utility, or anything else. It is simply that your results, for the same experiment, will be similar.