Like GetSatisfaction, stripped to its essentials this is "I have an authority domain and can rank for your brand name. Such a wonderful brand, would hate to see anything happen to it. $5,000 a year is cheap to you, isn't it?"
Seth can't get his new business venture onto the front page of the NYT by himself, after all -- he needs your legal department to make that happen. The rest of the Fortune 500 will promptly DDOS his order takers with their credit card numbers when that gets published. He'll also collect tens of thousands of links, many of them from authority sites such as TechCrunch, Slashdot, Consumerist, the newspapers which take direction from the NYT, etc etc, and as a result rank much better for other brands than he had previously.
If they're stupid, hopefully they're not so stupid that they'll ignore the lawyers who will say there is not even a scintilla of a case.
[Edit: Its not letting me respond because the site is worried I'm flaming you, which is totally not my intent.
In sum, litigation is a last-resort dispute resolution mechanism which you use to achieve business goals. Litigation here will not achieve business goals. On a totally separate level, which is academically interesting but only that, BigCo would be unlikely to prevail with a claim of trademark infringement.
There is no danger of confusion between Ford and Ford In Public -- it says "unofficial", prominently. There is no cognizable commercial damage -- Seth is not trying to sell cars. If you were a particularly bad trademark lawyer, you might argue that someone saying bad things about your brand causes you damage, but that cuts against a finding of trademark infringement, because it tends to demonstrate that the mark is being used, take your pick, transformatively, for identification ("nominative use"), and for purposes of commentary.
But, again, first rule of law for programmers: law is not program code, and litigation is not executing an algorithm. It is a negotiating tactic.]
Imagine a scenario where somebody makes a slanderous comment on some silly little web page that not very people know or care about. If his page becomes very popular, the financial damages may be almost entirely due to the fact that people saw the comment on his page rather than the original.
Anyway, didn't we banter about another company pulling an asshole move like this a while back? They set it up so it looked like companies that didn't use their service were neglecting their customers?
It's illegal to try to pass yourself off as someone affiliated with or endorsed by someone when that's not the case by using their trademark. The five instances of the word "unofficial" all displayed prominently above the fold on the Squidoo pages should take care of that.
Besides, Squidoo.com isn't an authority domain, and its "lenses" don't rank for anything on Google.
I personally found it extremely annoying when one of my projects was ranking first on aboutus as a simple stub.