At the very top: "It’s usually made from petroleum, which is better in a landfill than in a tank of gasoline"
"It" being plastic. The common non-plant-based kind.
And later: "If we're going to extract carbon from the ground at all, far better that it ends up in a soda bottle that will last 400 years than in the combustion chamber of your car."
It's good if there is more demand for non-plant-based plastic, because then we burn less fossil fuel.
>It is dumped in whichever way is cheapest and easiest
The most common way plastic is disposed of is in a landfill. The carbon is being sequestered underground, in other words.
Pumping oil into a landfill wouldn't be sequestering carbon, so I'm not sure why pumping oil, processing it into plastics, shipping it all over, and then dumping it in a landfill would be.
If that were the only thing that matters then the deepwater horizon oil spill would have been great, but there's much more to protecting the environment than CO2.
> You could do that by pumping oil into a landfill in a way that it can't be burned
It was, it's been their for hundreds of millions of years.