IANAL. IMHO That is up to each individual's decision. I actually asked them and they said they really don't want other people to embed comments on their website. BUT a case could be made about fair use, embedabble content and the fact that there is no effective terms and conditions on HN, just a FAQ (so I think they don't have the exclusive copyright of the comments). Plus the whole YCombinator ethos of asking for forgiveness instead of permission.

So I am discontinuing it just because HN is awesome and they asked nicely. But other people might consider things differently.