Search engines are generally considered fair use [0], at least in US. So up until HN doesn't send cease and desist, it's in the clear. Once it does, then it's all about what the claims are. Google litigated the crap out of this [1] over the years, so there is a positive precedent minefield all over the place.

[0] https://www.everycrsreport.com/reports/RL33810.html

[1] https://en.wikipedia.org/wiki/Fair_use#Text_and_data_mining