Proof: "They said they don't use private code. Either the private code appearing is published somewhere else, or they are using private code. Lying would be bad. Therefore the code is published somewhere else, and they don't use private code".
Proposition: "They either do not use private code or they did something very very stupid."
Proof: "Not using private code is very easy (for example google does not train its models on workspace users' data, which is why they get inferior features) and they promised multiple time not to use private code so doing in would be hard to justify"
Proposition: "They don't use private code".
Proof: "They said they don't use private code. Either the private code appearing is published somewhere else, or they are using private code. Lying would be bad. Therefore the code is published somewhere else, and they don't use private code".