If that black hole is 12.9 billion light-years away, it takes 12.9 billion years for the light to travel to us. Considering the age of the Universe 13.75 billio

If that black hole is 12.9 billion light-years away, it takes 12.9 billion years for the light to travel to us. Considering the age of the Universe 13.75 billion years, what they actually presume in the article is that we don't move at all: 12.9 (the time of the travel) + 0.77 (the age of the light) = 13.67, in the error margin of the age of the Universe (± 0.11).