Even 10xC? Even 10% of c! 40 years is not too long. We had that tech 50 years ago. Imagine had we been bold enough to send probes to Alpha Centauri. We could be expecting first hand pictures of an Alien system in the near future.
As you say, they do not say how that shape affects anything, just that they think it does, I can't help but refuse to hold my breath. I seem to remember something about neutrinos travelling faster than light not all that long ago. Talk is cheap.