[nerdsniper]

https://github.com/minimaxir/hacker-news-undocumented

Normally most users can vouch for flagged submissions. The fact that this is non-vouchable is interesting.

[teach]

Could it be that people who have commented in a flagged post are forbidden from vouching?

[nerdsniper]

That's my suspicion. Likely with an IP association as well for people with alt-accounts.

[muwtyhg]

The link you posted says users can only vouch for dead submissions, though?