I believe the article misses the point. What our observation are providing to us is a window into what the universe was like 12 billion years ago. This means that this hypothetically 'dead' galaxy has 12 billions years to evolve to where we are now, in the present. It may be that this observed activity is just a precursor to galactic development as we view it today. While the majority of the galaxies are expected to form between 500 million to 1 billion years after the Big Bang, I would guess that not all development should necessarily fall within this window. It may be that some galactic developments are more staggered than cosmologists have projected.
Additionally, if you accept the idea that the observable universe is like a message in a bottle that is cast into the sea, then you would realize that such calculations and measurements are limited to how one can observe the cosmos. Understanding that radiated signals, like light, can travel independent of their source, then one can logically hypothesize that there is no way of knowing when a radiated signal enters into our field of view. But the expectation is that the light is traveling faster than the expansion rate. Where this is not true, then the light will never reach us.
Considering that light travels faster than the expansion rate, then the limit of our observable perspective has been identified as about 14 billon light years, give or take a few billion years, depending on the instruments used. What we may not fathom is that the radiated signal may have been traveling for trillions of light years before it even entered into the field of our observable universe.
Example of visible distant not being the same as actual distance: Imagine the farthest observable distance. The CMB is visible at a distance of 13.8 billion years. If we could travel that distance, we would find planets similar to our own. Looking back from this distance, from where Earth should be, we would only observe this fog of the CMB. From this new distant location, 13.8 billion light years from Earth, we could leap-frog another 13.8 billion light years to observe a whole new cosmography. And there is no theory or calculation to preclude our ability to do this again and again, on into infinity. So scientists need to qualify their measurements as from within the observable universe, when discussing either its size or age. This does not diminish the importance of these calculations and measurements, but it does diminish their premise of conjecture for the entirety of the universal cosmology and cosmogony of its existence.