I'm having the same trouble. I've pasted the BusyContacts URL handler (busycontacts://show/{uid}) in the Contacts/Advanced screen in Alfred's Preferences. The only way I can get a contact to open in BusyContacts from Alfred is to uncheck the "Open Contacts in Alfred" box on the main Contacts screen. Leaving that box checked and hitting ⌘O still opens the contact in the Contacts app. Any suggestions?