Tom,
just stumbled upon this-
You wrote "If it were possible for any physical influence -- including gravity -- to propagate faster than the speed of light, it would also be possible to observe action at a distance simultaneously affect two or more spacetime separated cosmic events and we would be able to observe this correlation."
If the two events are separated by space-time then they are not seen as they were at the same time but a fabrication has been formed in which the two time separated events appear to be co-occurring in space-time. Even if the communication happens instantaneously, there will be a delay between that observed event. That's because of the space-time separation which means the two locations are not being seen at simultaneous times. The observed image is not a perfect replica of what is happening to the objects because of the distortion caused by the speed of light limitation. That's what I think anyway.