NOT a Joke or Troll
From my read it isn't a spoof or troll.
1. High profile events lead to poisoned torrents and scams everywhere. You may be a techie, but if you don't do your research and just grab 10 GB or hit shady domains, don't be surprised when it comes true.
2. There's no such thing as a free lunch, especially if you didn't do your research.
3. Also entirely true, although the theory that this anonymous journalist is covering his/her ass is a funny one. Given the tone, the Reg links, and the fact that it's published here, it's safe to assume it's a Reg hack who wrote this.
4. Bait/funny heading, but the point gets across. There were legitimate uses of the site, and users' stories have trickled out. This dump is a bit different in that some versions of the dataset are for simply checking hacked names and emails, sans credit card details.
"the respected expert and professional investigative journalist Glenn Greenwald" could be a bait line given some Reg disdain for him and "Snowden newsletter" The Intercept, despite the recent Reg-Intercept collab on Duncan Campbell and many recent examples of non-Snowden reporting. The two columns Greenwald has published about the Ashley Madison moralizing are worth a read (here's the other one).
That so many users rushed to call this a late April Fool's joke or fake/wrong is telling. It's clear from surveys that people really hate infidelity, but like most things people moralize about, the reactions are exaggerated, unnecessary, and damaging. Even those that cheated on their partner rather than get consent for using AM should be treated as victims of yet another data breach, rather than targets for online stoning.