I was actually thinking about this whilst lying in bed last night... insomnia sucks.
When putting your stuff online, be it blogs or photos, it becomes part of the public domain (it does not become licensed under the public domain, don't get the two mixed up

), like it or not google and other sites syndicate the content and cache it for future generations.
Now you can license your work through creative commons, or copyright the work, but those only limit what you can do with code (as in code examples), text, images, and your random thoughts (i.e. intellectual property).
Nowhere in any license, albeit creative commons, or copyright define to what extent you can view or modify content for your own viewing. You can't say that "you must view my ads" since this discriminates against the blind, or handicapped persons that make use of screen readers or people that view websites with the aid of someone else. You're not going to see someone read out that you can enlarge your penis or you are the 1,000,000,000 visitor to the site... they just read the content.
So Jack Lewis/Danny Carlton/whatever other alias he's going by, obviously has no grasp of the legal system. There are no legal provisions to protect against and define how a site can and can not be rendered, you cannot sue anyone that visits a website using Firefox because it's not your browser of choice, you can't sue Microsoft for providing the ability to disable javascript, etc etc. It's like a TV broadcaster saying that you must sit down during all of the commercials, you can't adjust the volume, nor can you change the channel.
His arguments are bogus, I personally spend more online than I do physically, and I only do it in Firefox because, lets face it, it's more secure and he's probably more pissed at the fact that people are blocking his religious dog ears (visit his site with IE and look in the corners), than anything else.
So when it comes to Firefox + AdBlock Plus' legal standing, it's all irrelevant. Firefox + AdBlock Plus shall prevail!