Calling someone and telling them you've found them to have violated a rule, and that there would therefore be certain consequences, is not an easy task, nor one

Calling someone and telling them you've found them to have violated a rule, and that there would therefore be certain consequences, is not an easy task, nor one that most people should be expected to do well. There's no shame in not being good at it. NumFOCUS should think about this. Someone in Jeremy's position could decide to sue them. They should think carefully about how these decisions are to be communicated to the putative violator and who should do it.