I've tried to make sure no one else has said this, so forgive me!
On the assumption that the ATC tape is in real time, what might have happened is this:
If the RHS was taxying the aircraft, then the Captain is doing the RT. He was given a "Give way opposite direction at KD" he then looks at his charts to try and find out where KD is. FO cannot see across and down to where the Comair is. Crunch.
Still not excusable, but understandable.
I have almost had a ground collision at Chicago where we had the 3rd runway change in as many minutes, I'm entering the data into ACARS and an MD11 appears from behind my screen pillar and goes right across the front. We were at a ground frequency change over point and he had been cleared by the other controller, but obviously expected us to be giving way to him.
The big surprise really is that there aren't many more collisions at JFK.