The article begins: "Closing his evening broadcast on Febrary 15,1996, poker-faced as ever, CBS anchor Dan Rather intoned: 'The same scholar who recently used his computer to identify what he says is an undiscovered poem by Shakespeare and got some high-profile attention for himself has unleashed his machine on author Anonymous.' "

"The statistical apparatus that forms the backbone of Foster's analysis has
led to a widespread misconception, the very one that Dan Rather mongered in his 1996 broadcast."

Quite possibly the author intended to insult Dan Rather. A monger is a small-time dealer in such commodities as iron, fruit, vegetables, and fish.
Quite different from a highly paid presenter on a multimillion dollar TV network.
It is also a bit surprising to see a former English professor verbing that noun.

He should get a flunking grade.