To be fair, you CAN monkey with timestamps and stuff in git. It is cryptographically proven that a given history results in a given commit hash, but you’re free to rewrite that and just have a new commit hash. If you give anyone else your repo, though, then if you rewrite history later they can be like “huh? this doesn’t match!”.

Not that that matters much here. Proving beyond a reasonable doubt is the goal, not Absolute 100% Certainty level proof.