You should be able to vouch that comment (click on it to do so, it'll be in the post-action links at top of comment). You can also email a vouch to HN's mods a

You should be able to vouch that comment (click on it to do so, it'll be in the post-action links at top of comment). You can also email a vouch to HN's mods at hn@ycombinator.com. They can remove flags directly, though the email lag response seems to be increasing (give it 24--48 hours), which makes direct vouches all the more valuable.