Everytime a jwz link is posted on HN I click on it, and it always works fine. Like just now for the above link.
Warning: it persists somehow, so you can't click on a link from HN, realise the problem, then copy+paste to correct it. Looks like you need to open an incognito window, use a different browser, or maybe otherwise clear your session.
Just delete the cookies of jwz.org (to be specific, the cookie called HN)
My apologies (I actually knew this, and forgot); unfortunately, I cannot edit my post now to advice people to enter the URL manually.
Is it known why this is happening?
He doesn't like Hacker News.
I mean, you can hotlink to jwz. There are just well-justified consequences if you do so from HN.