Good question. It’s likely that gamma jets point in random directions, but it’s been reported recently that planetary nebula have a preferred alignment.
http://www.fromquarkstoquasars.com/planetary-nebula-align-to-baffle-astronomers/
This is exactly what I was thinking of.
As our sun rotates around the galactic center, there is an excursion above and below the center plane of the galaxy, which our sun crosses, if I remember correctly every 250 million years or so. This happens because the plane of the Milky Way is a "Fedora" shape.
Some have corresponded the crossing of the galactic center plane with mass extinction events.
The orientation of black hole axes with one end toward the galactic center and the other end pointing out, would tend to make the center of the galactic plane the most likely location for a gamma ray burst that exits the galaxy.
With this particular burst lasting 20 hours, it makes an object crossing the galactic center and even greater risk of exposure to a burst than previously thought.
Why do such planetary nebula orient in this center to out direction?