Hey Miahi, I agree with what you, but I think Ifran's question is about why the light had to travel so far in the first place.
If you assume(?) that the maximum speed anything can travel is the speed of light, and ignore factors such as space expanding (redshift / inflation) then at .77bn years the radius of the universe would be .77bn ly, so the maximum distance between two objects (A & B) is 1.54bn ly. Now if light leaves A it has to travel that 1.54bn ly to point B; it shouldn't take 12.9bn ly to do this.
However, A and B aren't fixed points - so though the light from A is heading towards B, B is trying to run away (albeit at a slower pace). Here, Ifran's calculated the minimum average speed at which B would be running from A as .88c (if we assume that light from B is moving at c and not influenced by any interference, and that both A and B moved at c for the first .77bn years). That seems to be moving too fast, given at this stage in the universe's life the known/current laws of physics apply. Redshift can account for some of this, and Inflation means that the starting distance can also be much larger than the assumed 1.54bn ly, which hopefully explains the rest?