Please don't think that I'm defending anyone whose name might appear within the Ashley Madison hack which exposed member information ...
This said, I see three possible caveats to said information and a possible reason the hack may not have been activism - but somewhat maliciousness on the innocent.
1) There is a strong possibility that some of those signed up were looking for their spouse/girlfriend or past love interests for the sole purpose of curiosity or potential "divorce" evidence.
2) There were certainly some journalists and government domains and emails - I presume SOME may have been related to investigative purposes.
3) Ashley Madison (and earlier hack in May on adult friend finder) do not allow disposable credit cards. So, you had to use an actual credit card. I also suspect some of the people found were not REALLY the people who were on there - rather someone using their information.