> If a private key is copied, it must have been done so illegally or accidentally. Any other option means the cryptography is defective.

I agree if you're talking about an evidence such as a high-quality video or even photo with everything leading us to believe it's legit. However, we can not be as confident if we're talking about a BTC token. While extremely unlikely, there might be faulty algorithm implementations, problems with the algorithm, etc., that might lead to this situation.

Very unlikely? Sure, but we've to give the benefit of the doubt.