Said Dan Savage, when invited to express a "dangerous idea" that might "change the world for the better."
So, obviously, he's kidding, but what springs to a person's mind upon a particular prompting says something about that mind. You can't know exactly what, and, in fact, even when a person wants to be taken seriously and literally, you can't know that he's conveyed precisely what's in his mind.
We can only speculate what lies behind the outburst "abortion should be mandatory for about 30 years." I'd speculate that Savage isn't just pro-choice, he's pro-abortion. Not that he would require women to get abortions.
Mandatory abortions, of the sort done in China, are terrible impositions on a woman's bodily integrity. I doubt if Savage likes that idea — although it's possible that he gets a kick out picturing a forced abortions performed on socially conservative women whose offspring are too likely to grow up to be socially conservative voters.