Ah, see, now you've gone and done it. Now I have to get all lawyerly on you.
*sigh*
Apologies to anyone reading this post.
You cite to the United Nations Declaration. That's all well and good. It's a great document, with great goals.
It is not the controlling law in New York. In the state of New York (where all this happened), the law states that certain types of speech are considered defamation under any circumstances as long as they cause damages to the person. Defamation is not protected speech, and you can be sued for it. Here are the types of speech automatically considered defamation in the state of New York: “statements (i) charging plaintiff with a serious crime; (ii) that tend to injure another in his or her trade, business or profession; (iii) that plaintiff has a loathsome disease, or (iv) imputing unchastity to a woman ...” It doesn't matter whether it's opinion or not, it's still defamation. If you want a case citation for the above, look up Andrews v. Hansford Mfg. Corp., 2002 WL 193139 (N.Y.Sup., 2002.) on the Westlaw legal database (but be prepared to pay a small fee unless you own a subscription).
Alright, so I'm no expert on defamation law--I work for a judge who handles mostly criminal cases and social security appeals--but it really doesn't take an expert to see that this blogger hit two of the categories. Alleging that a supermodel is a "forty something" can't help her career. Even if she isn't forty-something, the fact that she looks it is not going to help her get her next modeling gig. So not only is it defamation per se, it also harms her financialy, which means she can prove damages, which means she can sue, and also means she will probably win. To be able to sue, first she has to know the identity of the individual, and for that to happen, Google has to reveal it. Bang, there you go, no violation of First Amendment because Google outed the blogger.
Furthermore, she called the model a whore, so you have the whole "imputing unchastity to a woman" thing. While this may or may not have caused damages this day and age (I don't know the girl, so I won't judge, but I do know quite a few women who's lives would be damaged quite a bit by being blasted as a whore by a complete stranger on the internet), it is still defamation per se under the law.
Now, there are defenses to defamation, cases where saying all those nasty things won't make you liable to suit, but that is a matter to be settled in court, but before you get to court, well, you have to know the identity of the blogger. Which is what happened. It may very well end up that this was protected First Amendment speech, but that's something that will be settled in court.
Basically, you can't throw rocks at people from the bushes and expect to remain anonymous.