I ran the following queries against my world database and I got mixed, but promising results.
Code:
update zone set safe_x = -1589.6, safe_y = 371.3, safe_z = -40.4, canbind = 0 where short_name = 'vexthal';
update zone_points set target_y = 371.3, target_x = -1589.6, target_z = -40.4, target_heading = 64.9 where id = 785;
After a quick reboot of the server, I found I can #zone vexthal and zone in to the updated coordinates and everything is great.. no problems.
But now here is where it gets.. odd. I zoned out to umbral plains and then zoned back into vexthal like a player would, except I didn't zone to the coordinates specified in the query above. Instead it lands me at the original zone in coordinates that were in the database before I updated it. And, of course, then I run into that same infinite zone loop.
I'll test this more tomorrow.