Grammatically, this sentence in the 2004 Platform appears to call for the legalization of child prostitution:
We call for the repeal of all laws that restrict anyone, including children, from engaging in voluntary exchanges of goods, services or information regarding human sexuality, reproduction, birth control or related medical or biological technologies.
This was perhaps somewhat accidental, since the 2004 reformatting project dropped a crucial "therefore" that in previous platforms connected this sentence more explicitly to its context:
We regard the tragedies caused by unplanned, unwanted pregnancies to be aggravated, if not created, by government policies of censorship, restriction, regulation, and prohibition. Therefore, we call for the repeal of all laws that restrict anyone, including children, from engaging in voluntary exchanges of goods, services, or information regarding human sexuality, reproduction, birth control, or related medical or biological technologies.
But there is ample precedent for the LP Platform to push the envelope in the area of treating children as adults. Introduced in 1978, the Children's Rights plank was notorious before it was finally removed in the 1996 Platform. The 1978-1982 version of the plank put "children" in scare-quotes when it said:
We believe that 'children' are human beings and, as such, have the same rights as any other human beings. Any reference in this Platform to the rights of human beings includes children.
Even until the 1994 platform, the plank went on to call children an "artificially defined sub-category of human beings". Indeed, the 1990-1994 platforms categorically advocated "the repeal of all laws regarding consensual sexual relations, including prostitution and solicitation", and we know very well that Libertarians mean "all" when they say "all". Only in the 1996 house-cleaning did the Platform first make an age distinction regarding sexuality:
We affirm the right of adults to private choice in consensual sexual activity.
The 1984 platform also had this egregious language:
We also support the repeal of all laws establishing any category of crimes applicable to children for which adults would not be similarly answerable
The sentence continued with "such as curfew, smoking, and alcoholic beverage laws, and other status offenses", but the problem was still glaring enough that "answerable" was changed to "vulnerable" by 1990. It wasn't until the 1992 platform that the Children's Rights plank added any acknowledgement that guardians might have some power over their children. Since as far back as 1984, the plank had mentioned "guardians" only as people who provide "care for their children" and perhaps "administration and protection of their rights" — at least until the child exercised her right to either take over these tasks or seeks better guardians. Except perhaps for that word "administration", the plank was exclusively about insisting that children had either equal rights as adults, or extra rights in terms of switching or ditching "guardians", and not about admitting children ever had less rights. In 1992, the plank finally "recognize[d] that children who have not reached maturity need guardians to secure their rights and to aid in the exercise of those rights", but even that language is extremely vague about what it's actually recognizing.
In 2000 the Family Life plank was rewritten as a Families and Children plank, and finally took a stand against child abuse and abandonment:
Parents, or other guardians, have the right to raise their children according to their own standards and beliefs, without interference by government, unless they are abusing the children. […] Parents have no right to abandon or recklessly endanger their children. Whenever they are unable or unwilling to raise their children, they have the obligation to find other person(s) willing to assume guardianship.