The best way to provide feedback is by emailing hn@ycombinator.com. I've received a reply to literelly every email I've ever sent (all credit to Dang and Co for being extremely kind and consistent in supporting my inner troll rehabilitation effort).

There is no site mechanism to alert moderators about @mentions, and due to sheer volume of messages the site operators will typically never get to see your well-intentioned message.

This thread does have better odds of being read than most, though :) cheers