In the meantime, someone else (here) reported killing Zixzax a couple times got him to open the next room. Teleporting him might reset something.
Hi Raze,
Thanks for the suggestion. Unfortunately, we found the same thread last night and tried teleporting Zixzax around homestead with no luck. He finally became tired of our "antics" and promptly destroyed our party (Zixzax is lv. 26).