That won't help. The closest GRB we've detected was about 100M light years away, so well outside the galaxy. If we had one happen within our galaxy that's beamed towards us, I don't think that 10ly make any practical difference in the 1/r^2 attenuated flux. Also, the beams are thought to be several degrees wide, so unless it's a very close GRB (in which case we should consider other problems), it's also unlikely that 10ly would move is out of the beam.

Source: former astrophysicist. Also if I remember correctly, the Wikipedia article on grbs is actually decent. (Edit: overstated things - need coffee, I suppose)