The concept of "cosmic neighborhood" is deliberately left a bit vague in my description, but it definitely doesn't mean the stars that were near the sun when th

The concept of "cosmic neighborhood" is deliberately left a bit vague in my description, but it definitely doesn't mean the stars that were near the sun when the sun was born. Rather, it refers to those stars which are within reach of us, now, in a timescale that is short relative to the typical interval between births of civilizations that distance apart. That could be anything from a corner of a galaxy to a galactic supercluster, depending on the speed with which civilizations can expand and the frequency with which new ones arise in the universe. Note that if civilizations expand at sufficiently close to the speed of light, then there is only a tiny window of time between when their light arrives and when their colony ships do. So under this model, it is quite unlikely that a new civilization waking up for the first time would look around and see anyone. Most likely, either the light from those other civilizations hasn't yet gotten here, in which case we see nothing, or their colony ships have already gotten here, in which case we wouldn't be born in the first place.