I'm pretty sure everyone would take that position so I'm confused why you're implying I wouldn't.

"authorities currently favor one explanation for the pollution"

Tells me that they don't have proof this is the source of the PFAS pollution. If they did, they wouldn't "favor" the explanation, they would just say that's the explanation. I don't support making wide changes based on hunches. Sure - replace the fertilizer with something else for a while and see if that changes the PFAS levels. If it does, sure ban the paper products from being used as fertilizer. But there is a cost associated w/ doing that and that cost has higher-order effects.