I'm also not a lawyer, pleased to meet you.
> I sort of directionally think that if WPE had a strong case here, their opening bid wouldn't be a C&D
I believe, as a non lawyer, in some places to be able to sue for defamation you must first contact the defamer and demand they take it down.
I have no idea and no opinion if there is a case. If there is a case a C&D might be a necessary step.