I think you may have had it right the first time. I have the original DWB manuals in front of me. Good thing that I didn't post earlier with a guess as to what DWB meant. These books are labelled "UNIX System V Documenter's Workbench". They describe the following programs: mm, troff, sroff, nroff, tbl, pic, and eqn.

I have throughout all of my unix text processing docs. I can't find any mention of a sexist filter. The style/diction/explain programs came out later. They, as supplied, do not address sexist constructs. With a non-standard data file, I suppose that they could.