It was pointed out by an astute user in the wordpress.org forums that my readme file had a mistake…
http://wordpress.org/support/topic/plugin-wp-members-not-blocking-pages
I basically wrote things backward in the readme file.
Had I worded it correctly, it is supposed to be intuitive:
- if default = block then unblock = true to unblock
-OR-
- if default = unblock, block = true to block
