It was just a story that caught my eye and made me say "Hmm…neat!".

Like so many pure science stories, the layman's headline for this one is "Scientist thinks up plausible guess–mystifying, obscure measurement becomes merely obscure." It's mildly relevant to interstellar travel, and it will influence other scientists' theories, but that's probably about it. (That's not to say it's useless–if Aristotle had accurate theories about how hurricanes work, not many of his contemporaries would care much, given how rarely hurricanes affect shipping in the Mediterranian–but a millenium or two later, it might be considered the most important work he ever did.)

I was running the risk of using exactly the same terms as the article in my summation and figured that approximations would work.

Hoping that the science journalist was giving an accurate precis of the facts? In my experience, the odds are not good.

Really, the gas is being evaporated by the shockwave.

Still trying to approximate what's going on in terms that your audience can relate to? I'm not sure that's any better–gases don't evaporate. "Dissipated" is a better word in this case, I'd say.

The gas that should be there is being destroyed, the new theory says, by the shockwaves from exploding stars

OK, just to be pedantic–"destroyed" isn't the word you want there. The black hole should gobble up any gas in the region that gets cool (that is, slow) enough. Supernova shockwaves heat (accelerate) the cooler gas, without as much effect on gas that's already hot. At least, that seems to be the theory. Thus, the gas gets a chance to leave the area where it's in danger of being swallowed by the black hole. Left unexplained is where that gas ends up….

so the gas that should be there gets the brunt of the energy and disappears.

From that area, not altogether. Matter is still conserved. (OK, mass-energy, but in this case calling it 'conservation of matter' is probably an accurate approximation.)