My thoughts exactly! How do they know what the hydrocarbon of the earth was BEFORE the event? The impact likely liquefied the earths crust in a certain area and superheated and ignited the oxygen in the atmosphere.
They have no idea what they are talking about and can speculate at best. Note that EVERYTHING didn't die. BUT everything needs sunlight and vegetation. I'm sure if they can get more money they can come up with other interesting questions to answer and problems to solve.
A lot of meteors are carbonaceous chondrites. A HUGE lump of coal.
Well, as Enrico Fermi said to Robert Oppenheimer during the Manhattan Project that ended WWII, “This is superb physics”.
Thus, certain things do get done. And we do know a little about a lot.