I imagine you'd be right. I was pretty disappointed a few weeks ago when I read that Lincoln's motives were more political than altruistic. Pity.
Lincoln was certainly a master politician and thus he never forgot the political angle to any particular problem he encountered. Having said that, there's no reason to believe he couldn't be both political and altruistic. I suggest you read a very fine volume, "Lincoln's Virtues", on the development of Lincoln's moral code and viewpoint prior to the Civil War.