I think they can say they feel it borders on unethical (which is the impression I got from it). Along the lines of: "ok so you can block our ads, but that's a bit sucky guys :("
On the topic of your article (I assume it's yours?):
I pay for a book, and then I read the book start-to-finish with no ads, no distractions. A few pages at the back maybe, but I can ignore those. Books are nice.
I assume you can see the difference here?
In terms of forcing you too look at the ads. I dont think the ars article tries to imply that either. They are saying they would appreciate it if you looked at their ads. Please.
I dont know if you have seen the ars site with ads but they are one I personally unblock: they aren't particularly in your face, are generally aesthetically pleasing and I also like their content (some of the best on the web). Encouraging that approach is a plus IMO.
If I had to generate revenue to keep my sites going, I would find a way other than advertising to do it. Or I'd shut them down.
Seems a "shoot yourself in the foot" scenario. Chances are people wouldn't actually pay monetary cost for your content - people hate doing that generally. Adverts are "zero cost" to a consumer :) most are happy to swap free content for a few adverts.
Why is it unethical, as your seemingly suggesting, to do that? :)