It is true that natural processes are all an atheist has assuming, like the vast majority of atheists, the supernatural is categorically rejected. From that it doesn’t follow that an atheist is obligated to subscribe to some particular natural explanation, or to any at all. I subscribe to abiogenesis in the sense that it, or something very like it, will likely gather enough evidence to be considered the scientific consensus (it arguably already is, but I’m riffing on the technicality that it’s not falsifiable at present and may never be). If I didn’t subscribe to abiogenesis then I would say that I don’t know how life came to be and would wait for an explanation I felt there was sufficient support for.
I am not making an argument from ignorance. I’m admitting ignorance. Which is a very different thing. The problem comes when people start making stuff up in a furious attempt to be knowledgable when sure knowledge isn’t obtainable.
I prefer to frame it as being able to sit with uncertainty or even having no idea about a particular topic. I think not knowing or not being sure has a stigma it doesn’t deserve, in between a lot of people’s ears.
It is liberating only in the sense that I don’t have to cover for ignorance or uncertainty like it’s inherently shameful. Willful ignorance about settled science or known data is one thing; being in a pre-knowledgeable yet receptive state is another.