Let's go through this again:
Dougherty (aka canon) said "we (the Federation) have the planet" aka the planet is definitely not independent.
The problem with this argument is that you're presuming that Dougherty is speaking legally and formally when there is every possibility that he is speaking quite informally, in terms of the Federation's
de facto control of access to the planet rather than actual ownership
of the planet.
And the problems with your argument are:
-that Dougherty directly said the federation has the planet aka it is not independent (your convoluted interpretation doesn't change this in the least);
-that Picard confirmed Dougherty is speaking "legally and formally" when saying the planet is not independent by NOT contradicting him on this essential point (with ANY arguments, whether legal and moral).
Any half decent diplomat/reasonably intelligent person would contradict Dougherty regarding this point on which their entire discussion hinged - if this diplomat/person (aka Picard) has any arguments to contradict with, that is (your convoluted interpretation would have Picard be an incompetent moron).
Because, really, how, under Federation law, could they possibly own a planet that was already inhabited and owned by a foreign culture before the Federation existed?
First - it's not proven (not even close) that the ba'ku settled the planet before the federation existed.
Second - your own country owns a lot of land that "was already inhabited and owned by a foreign culture" before the USA existed.
All planets in federation space are owned by the federation, EXCEPT:
Those recognised as independent by the federation (not this planet);
Those where the Prime Directive applies (not here, regarding the ba'ku).
Picard did NOT contradict this point (by using legal or moral arguments); he went ahead with, '~nevertheless, we should let the ba'ku alone, because - insert moral argument'.
Picard invoked the Prime Directive. Dougherty (aka canon) said it doesn't apply + he explained why this is the case. Picard did NOT contradict him (by using legal and moral arguments).
The fact that someone else did not pursue every possible legal argument against a statement that was itself not a legal argument does not constitute evidence of lack of such legal arguments.
This goes far beyond "someone else did not pursue every possible legal argument".
Picard did NOT pursue any argument (legal or otherwise) to counteract Dougherty's
essential points that the planet is NOT independent and that the Prime Directive doesn't apply (apropos this, Picard was the one who mentioned the Prime Directive, only to be shown how it doesn't apply and be left with no counterarguments regarding the issue).
Picard NOT contradicting these ESSENTIAL points Dougherty made means Picard did not have the arguments (legal or moral) to contradict Dougherty. Alternatively, Picard was mentally challenged.
Or, alternately, Picard felt that Dougherty would continue to issue illegal orders and further legal arguments would be a waste of time.
O, but Picard did NOT feel further "arguments would be a waste of time".
Indeed, he went on and on with morality and rhetoric - and never once invoked a far more powerful legal argument - because he had none or because he was mentally retarded (take your pick).
Either way, the fact that Picard did not pursue every possible legal argument does not constitute evidence that such legal arguments are invalid.
Already answered.
And just because you keep repeating this doesn't make your interpretation less of a convoluted mess.
Have you ever been in a court of law? Had you any tangent with the law? It's law and jurisprudence that matter; if moral/sentimental arguments are used, it's only in order to convince a judge or whomever to interpret a law in a specific way.
And neither Picard nor Dougherty were in a court of law. I'm sorry if you're under the impression that everyone speaks like lawyers at all times, but it's simply not the case. Especially not officers in the field. And especially not in action movies.
If you're under the impression that the law is only binding in a court of law, you're wrong. The law is binding everywhere.
And if you're under the impression that diplomats don't invoke laws (if they have any laws to invoke, that is) when discussing the legal status of something, you're wrong.