Are you for my right to choose to hit your face? Or, would you say that you are "anti-choice" on that issue?
When you understand why you are "anti-choice" on that issue, you will understand why I am "anti-choice" on the murder of young humans.
And, maybe you will also understand that harming another individual without justification (we call that "aggression" or "aggressive violence," as opposed to "defensive violence") is not a "choice." There is no legitimate moral choice for individuals to engage in aggressive violence. Granted, you have the free will to make that choice in fact, but that is why we have courts...to handle those who freely choose aggression/victimization. It is not a legitimate choice. No moralist would support that choice. There has to be a justification for violence (e.g., self defense); only then do you have a legitimate/legal/moral choice to engage in violence. You still don't have to do it, but at least you have a moral choice potentially available to you.
Libertarians are for freedom of choice on all issues in which there is no victim. Do whatever you want as long as you aren't hurting anyone. But, we don't recognize a right to choose murder, because there is a victim. Once there is a victim of an act (a non-consenting party), then you have no legitimate choice, and you are morally (and should be legally) restricted from victimizing that person. No moralist (theological or otherwise) recognizes victimizing someone as a true "choice." This is the fundamental principle of secular law in all civilized societies. That is why I am against abortion. That is why those who support the right to abort have to jump through all kinds of hoops to try to justify it, and will even admit that it should be reduced because they know it is an aggression (and they know they need a justification to justify violence against another human). Many fellow libertarians are for the right to abortion, but in order to get to that position, they have to define the unborn baby as a non-human, to define the victim out of existence through sophistry that goes against biological science. That is basically what Hitler did (since you recently mentioned him, I will assume the prohibition on doing so is removed for the time being); he made certain individuals sub-human, stripping them of their right to life. Stripping humans of their most basic human right is a road that I think we should avoid for obvious reasons.