Heterotrophy is kind-of allowed after you have an ecosystem of creatures that are messing about with organic chemistry as part of their living processes. At that stage there might well be an organic soup created by their waste products, decayed carcases, etc.

This autotrophic vs heterotrophic scene is your area interest - and efforts to paint Cairns-Smith as a heterotrophic theorist strike me as a bit of a misguided smear campaign. His proposed earliest creatures are made of clay! They "eat" supersaturated mineral solutions. You can't get much less "organic" than that.