I've been noticing these ostensibly irrational posts for months. Some of them are likely Obama supporters IRL.
You're right that no rational pro-lifer would find Obama (who opposed the Born Alive Act, attacked the Catholic Church's right to religious freedom regarding life issues, and instituted Obamacare, which increases abortion funding as well as the number of abortions) preferable to Romney, who holds the exact opposite positions.
Romney is not pro-life.
Because a person points out that Romney is not pro-life, only translates to the confused as support for obama.