It assumes a hard step between wildlife and sapient life, but it makes no assumptions about earlier hard steps.
I suppose it’s not likely to be a hard enough step that creating enough life to massively outweigh it is all that hard. Wildlife will only live on the surface of one planet. Sapient life can live on many planets, and can mine them as so to use all the matter.
It assumes a hard step between wildlife and sapient life, but it makes no assumptions about earlier hard steps.
I suppose it’s not likely to be a hard enough step that creating enough life to massively outweigh it is all that hard. Wildlife will only live on the surface of one planet. Sapient life can live on many planets, and can mine them as so to use all the matter.