Sorry, but I don’t understand why this would be a problem? Can you explain seriously why the “existence of a case” is too much to admit, while there were several messages above implying that such cases already exist (or did exist in the past)?
I also think the PSF has a moral responsibility to inform its members of its tasks and activities, when asked about them. You could perhaps do so in private when very sensitive, but you should certainly not brush away such requests by claiming that giving any information, however anonymized, is too much.