That is the case. Specifically:
I am the super admin of the vBulletin site, and in the "Administrators" primary group.
In VW, all permissions for that group are "Yes", specifically including all varieties of "Can Edit..."
Additionally, my particular user account is setup as a Wiki Moderator, with "Use Custom Moderator Permissions" as "Yes", and every permission (incl. "Cant Edit..." variations) set to "Yes".
... still, I cannot do anything to pages authored by others, who set "Collaboration Prevention" on; such pages become effectively read-only to me.
This seems like either a problematic design (precluding admins/mods from doing their thing) .. or .. a bug?