callipygian50, you've gone off on a tangent regarding competence for entering into contracts, which isn't really relevant.
I don't think any of the analogies I list are tangents. I agree I have shifted from abortion, to other rights. I did so to focus on the structure of your argument-by-question (which appears to contain a logical fallacy.)
You seem to be wanting to make an argument by asking a question. The question you pose appears to attempt to show that libertarians thinking abortion should be legal exhibits some logical inconsistency. However, there is no logical inconsistency.
The various analogies I discussed were brought up to mimic the pattern of your question. The obvious answer to the questions ought to show you two things:
1) This idea if
someone is a legal person in sense "X", do they get automatically gain unrelated right "Y". No one thinks this position is inconsistent. (Examples include contracts, right to drink, right to vote, right to reside in the country etc.)
2) Any "inconsistency" one might see in (1) above seems to arise only when someone edits out the question in a way that leaves "legal person" ill-defined. So, by editing out the text "in sense X" and asking whether a person should have right "Y", you end up with what amounts to a rather silly question. No one can really answer it because "legal person" has no specific meaning and can't tell us anything about the full collection of rights a person ought to have.
As it happens, by failing to define "legal person", your question (and implied argument) is the sort that leads to the logical fallacy called "equivocation". A good discussion is here:
"Equivocation is the type of ambiguity which occurs when a single word or phrase is ambiguous, and this ambiguity is not grammatical but lexical. So, when a phrase equivocates, it is not due to grammar, but to the phrase as a whole having two distinct meanings.
To avoid ambiguity and equivocation, you need to specifically define "legal person" based on some collection of rights. If you do that, I think you'll discover if you specifically define what you mean when you say "legal person" while asking your question, it will either
a) Be obvious you are asking a circular question (as ironman said) or
b) It's perfectly logical for someone (including a libertarian) to think a fetus is a "legal person" by some definition and think abortion is legal.
So, yes. I discussed contracts. But the structure of your argument by question should work for other rights. It doesn't. And the reason it doesn't is that you aren't defining important terms, and the ambiguity in your question results in equivocation.