You really minimize the importance of the sacred oath every congressman takes to support and defend the Constitution of the United States. "Little symbolic State's rights" is the fundamental characteristic of our Constitution and our form of government. You're not suggesting he should ignore his oath if he believes that he has no Constitutional authority to pass those laws, are you? Such drama.
The Republican Platform advocates a Constitutional Amendment.
He's running for the Republican nomination.
Obviously he can change the platform, but taking a pro life stand on this issue is a no brainer for a Republican.