Earlier quoted context omitted.
To be blunt your argument for polluting our environment doesn't feel like it's in good faith when you blame wood for being a pollutant until a fungus showed up hundreds of millions of years ago. I absolutely loathe the term "whataboutism" but this seems like a real example - "what about the fact that wood was a pollutant hundreds of millions of years ago? We should be able to dump plastic now".
His point is that nature adapts to these things and learns to consume them eventually. There is nothing intrinsically wrong with storing plastic in the earth, as long as it isn't disrupting ecosystems.
The point is that from a human perspective, and from the perspective of most multicellular organisms, plastics discarded into the environment are a really bad thing for our health.