Vouch them and/or email to hn@ycombinator.com and say why you think they deserve to be [undead].
I see that a lot, some have been erroneously caught by the real time AI detect filter (which actually isn't too bad at slicing out the actual AI gen comments) others have gone hard against the zeitgeist.
I've had the mods reinstate comments that I've thoroughly disagreed with but were making their best case for an opposing view - the threads are better with the best arguments forward for all sides of the elephant.