'that page'???
Lets be a wee bit more specific about 'that page'.
Sounds like a quote from a Monogram Close-up which are filled with errors.
Strange that there is no record of any test firings or 234 pilot's combat reports saying they fired the guns in the B-2 or enemy pilots reporting being fired at when attacking the 234 from the rear.
My first post was badly worded, so let me re-phrase:
the B-2 did not have any rearward firing cannon fitted