Thank you for looking into this. There is some argument about perfect proof, or whatever you call it. However, as it happens, in my past I spent a lot of time drafting legal documents corresponding to U.S. standards, which served to protect deals in the hundreds of millions - not against such form of theft (although there were court cases), but against any other foreseeable contingency. The appropriate term would be 'beyond a reasonable doubt', as 'could reasonably be inferred.' Beyond the answer formulations that I recognize as my own, even without the context of having written the answer, look at - surprise - labelling the same two lines with (1) and (2) for future reference. How likely is that?
Please do accept my thanks for taking the time to look into something that is certainly not what this site should be about. As I said recently at another occasion, I would not want to be a moderator of a site of this magnitude, and certainly appreciate the effort of anyone involved in maintaining this site, and devoting so much of their own time to administration too.
Edit (02/26): deleted an irrelevant 3rd paragraph