A serious discussion of the safety of birds would sound very different, but that isn't the goal. The goal is to talk about anything other than reducing fossil fuel production.
This is a monumentally stupid apples and oranges “gotcha”.
Natural vs. unnatural is irrelevant though. "Nature" is normally out to kill you for its own benefit and does not care if the planet or any of its lifeforms survives. What matters is our interests in preserving the world we know or improving it in our eyes, and picking the best option for that.
The option that minimizes worldwide cancer development and doesn't screw up weather systems and various biomes would be the winner in that regard.
I'm curious, what are you thinking of when you say 'natural processes'? I hope it's not cats.