There's also a model-attribution problem here.
Calling the Fable API does not prove Fable generated the response. Even if supposing Moonshot sent a request to the Fable API, if Anthropic suspects that its a distillation request, then the requst will be secretly redirected to Opus.
So Moonshot would then receive an Opus answer, not a Fable answer.
So even if the logs prove Moonshot extracted answers from Claude, but they would not automatically prove those answers came from Fable specifically.
To prove that Fable is related to K3, you'd need to show the served-model ID for each completion, the extracted corpus that is linked to K3 training jobs, and model-lineage evidence like a canary transfer, unique error fingerprints, or an ablation.