The site was just down for several days, apparently due to high amount of comment spam so likely that’s why they are now extra fussy about the what accesses it and where from.
The site has been block-happy for a long time. Every time it comes up on HN or Twitter, it's a gamble if whatever ISP I'm on at the time is in good graces right now. But I can somewhat sympathize, spam-fighting sucks if you're caught in a wave of it...