It looks like a clash between two wavefronts rippling along the front collision, rather like a thought experiment I've seen before. Imagine two vast sheets of plywood floating in space with the near edges only slightly separated. At one end, the separation is four inches. At the other end, the separation is one inch. This is because one sheet is very slightly out of square, whereas the other is perfect.
Accelerate one sheet so that it passes under the other one. The one-inch gap is closed first. The visible separation between the sheets disappears at a "point" which ripples along the boundary of the upper sheet at speeds not constrained by the speed of light. If you accelerate the sheets together at near light speed, the "point" flies at some amazing hypervelocity. But it's not a real object or even a real signal.
I may be misinterpreting the main article, but that's what I get from the "interference" between two wave fronts.
Dang, you beat me by a minute, but I agree with you.
This reminds me of a question I have about Star Wars Physics. Has anyone ever calculated the apparent speed of the wave front in the exploding planet? My guess is the debris cloud is traveling considerably faster than the speed of light.