Simultaneity is only defined when you talk about two (or more) events. The discussion was about an event: the collision of two stars. What is the other event?
The generous interpretation of what he means is that considering that this event is outside of our past light cone, there exists an inertial reference frame such that the collision happens “after” our “present”.
Of course, relative to our own inertial reference frames as we experience them, i.e. where we are mostly not moving, the collision would be thousands of years in the “past”.
When he says “in our frame” he is clearly at least slightly confused.
Of course, relative to our own inertial reference frames as we experience them, i.e. where we are mostly not moving, the collision would be thousands of years in the “past”.
When he says “in our frame” he is clearly at least slightly confused.