Fortunately there is nothing else the state forces you to purchase so this is a very clean ideological point you are making.
Libertarians should be protesting against violence toward the unborn child... libertarianism's core principle is nonviolence towards others.
I've always held that one can make a principled, well-reasoned Libertarian argument both for OR against abortion, based on the grounds you just cited. But I've also personally always held that there is no objective, universal standard for deciding exactly when to consider that unborn entity a "child" which has rights and against which it makes sense to speak of violence being conducted. That being the case, I don't find any value in adding the specter of State violence to the mix. I'd rather leave this whole situation to the mother, her family, medical professionals and others supporters.
This is why I'm a Libertarian who largely opposes abortion on a purely personal level, but is 100% pro-choice on a political level. But at the same time, I can respect those who hold the other position based on the NAP. I'd just argue that with no objective way to resolve the dispute, it's best to not bring the State into it.
If you take libertarinism to it's extreme like that then they should be protesting the lack of freedom of association as well but none are doing that either.
But freedom of association is legal.
No. You're legally not allowed to discriminate among customers, employees, neighbors, or renters.
Would that not be freedom of disassociation?
I agree, but I also tend to think this battle was lost when the SCOTUS refused to reject the "individual mandate". When you've reduced the notion of individual agency to the level that the State can dictate what items you must purchase, this is an entirely logical consequence.