As far as we know life is only present on Earth, we presuppose that in the vastness of Cosmos there are other instances of it or that it can re-emerge from almost zero, but the reality is that we simply don't know. So maybe there is a possibility that wiping out all the life on Earth also wipes it from the entire Cosmos, forever.
"Humanity" is far from "all the life on Earth". Nature will be better off once it happens.
Or perhaps the comment you were responding to was asserting "knowing" or "caring" is not something Nature can do.