I think Wm was lying when he said that...
If you recall--- the end of Romeo and Juliet...
Juliet has just revived from the sleeping potion--------to find Romeo deader than a door nail next to her...She is distraught---
And she says " Romeo oh Romeo--- Hast ye drank it all, Couldeth thou have not left a dash for me....For I would rather die than live in em-dash hell without you.... I shall have to dash out my live on your short dash sword... (then she runs to his sword and grabs it==== comes back and kisses the dirty rotting corpse that was once Romeo) and says " I hereby declare my undying love you, Romeo as I dash my life short with your dash blade" then plunges the blade into her heart...
With all the references to dashes he made, I doubt he hated the dash....I think it was just the em-dash he hated.......... I also bet he made lots of pe-dashes in his life.