There is a big difference between not having any legislation on the agenda and not taking any action on abortion... He has already said he would defund Planned Parenthood, reinstate the Mexico City policy, reinstate the policy forbidding abortions at federal military facilities, etc. I think Romney will appoint pro-life judges and justices. But his campaign is about the economy - so should he start promising to put abortion legislation ahead of that? Especially since we, as conservatives, have long held that the Federal government never had any business interfering with the states right to regulate or ban the practice in the first place?
If Congress hands him a bill to sign that deals with the topic, he might do it. At most, the waffly wonk is promising he’s not going to stump for any sort of legislation dealing with the topic. Which given Congress’ proclivity for gluing together disparate topics in one bill, is likely not going to be a promise kept very long.