Seems like that should be pretty easy to stop. Birnessite can break down prions[1] and isn't particularly rare (assuming they don't already account for that).
[1] https://news.wisc.edu/common-soil-mineral-degrades-the-nearl...
[1] https://news.wisc.edu/common-soil-mineral-degrades-the-nearl...
From your link: "The new study (...) was conducted on prions in solution in the laboratory". "The next step (...) is to mix the mineral with contaminated soil to see if it has the same effect". "I expect that its efficacy would be somewhat diminished in soil".