This defense doesn't work for the torrent aggregation sites (Pirate Bay, Isohunt, etc.) and it would only work here if the various spam lists really were willing to staff the "unlist us" addresses as thoroughly as the "list us" addresses.
I work at a nonprofit that has health care and gang outreach as two chunks of what we do. I have had emails inviting a group of people to a meeting around gang violence flagged as spam in the past, because the subject line was thought to be spammy. Heaven forfend that one of our providers should dare to talk about viagra or erectile dysfunction in an email.
I am not sure if it was Spamhaus per se, but one of the times we were added to a blacklist, I was able to get us pulled immediately. But I was warned by the fully automated removal system that that was a one-time deal and if we were listed again, I would have to wait patiently while they got around to deciding what to do.
With the Barracuda list, there's a for-profit company with 800 numbers that are answered, at least. I don't remember now who it was, but one of the RBL providers got into a pissing match with Yahoo over their mailing list configuration and blackholed Yahoo's outbound mail servers a few years ago.
Accountability with these lists is a problem. The court case immediately at hand isn't interesting one way or another, since it wasn't contested.
Accountability, on the other hand, is something that needs to be addressed a lot better by the RBLs.