I think it's almost certainly a hoax. Knowing how universities work (though not Yale specifically), I'd bet that the prof was in on it, but that the university leadership didn't even know the content of the exhibition until someone complained.

That said... while I know you disagree with me on this, surely you can recognize that there's a big difference between thinking that women ought to have the legal right to terminate pregnancies if they believe it is the best course of action, and thinking that having an abortion (or inducing a miscarriage) is morally trivial. There are plenty of things that I think folks ought to be able to decide for themselves that are of the greatest moral import. The mantra of at least one strand in the abortion debate (including, in my experience, most of the folks seriously involved in pro-choice policy, as opposed to internet crazies), is "safe, legal, and rare." Yeah, there are folks who think that abortions are no more morally fraught than appendectomies - but they're only one faction in the pro-choice camp, and not, I think, the mainstream.