You’re safeguarding against the wrong thing. If I needed to fake a prediction that badly, I’d find a security hole in Less Wrong with which to edit all your comments. I wouldn’t waste time establishing karma for sockpuppets to post editable hashes to deter others from posting hashes themselves, that would be silly. But as it happens, I’m not planning to edit this hash, and doing that wouldn’t have been a viable strategy in the first place.
You’re safeguarding against the wrong thing. If I needed to fake a prediction that badly, I’d find a security hole in Less Wrong with which to edit all your comments. I wouldn’t waste time establishing karma for sockpuppets to post editable hashes to deter others from posting hashes themselves, that would be silly. But as it happens, I’m not planning to edit this hash, and doing that wouldn’t have been a viable strategy in the first place.
“Clearly, the way to make our safeguards super-secure is to make yet another comment with the hash.”
“Clearly, the way to make my safeguards super-secure is to make yet another Horcrux.”
Somehow, you could only see through one of these strategies.