Needed to post this to help any other poor soul trying to get Wordpress to provide an AJAX service to non-logged in users. Note this is only necessary if you've got a plugin active that bans front-end users from back-end functionality. Most of the front-end login plugins do this.
Bespoke content management systems are nearly always just vendor lock-in. There, I said it.
Hopefully Google will index this and some hapless business owner will avoid commissioning a web agency to implement their website using a proprietary CMS.
