The clever part here is the 'private' account. The usual defense against a Sybil attack bruteforcing a predictive track record is simply that people can keep re

The clever part here is the 'private' account. The usual defense against a Sybil attack bruteforcing a predictive track record is simply that people can keep records or notice that whole swathes have been deleted. The private account here ensures Twitter will vouch for the timestamp, but no one can see them until after, and the privating is itself hidden/secret - you can't tell when an account was private (at least, not without access to fancy proprietary datasets).