The opinions you repeat and repeat (the baku are not trespassers, etc) are based on nothing but hand-waving and rhetoric; as such, they have no worth.
I also believe the Baku and Sona are not trespassing. They were there before the Federation, Romulan, Klingon empires were formed. When did they star trespassing - a hundred years ago, 50 years or when the Federation saw something it liked.
Thats like saying the Australian Aborigines are trespassing on Australia in the British Empire. Aren't we better than that now?
Saying that the Federation is a recognised power is correct but not by all. The Federation has 'rights' in the area relative to the Romulan and Klingon empires because presumably of military and political machination.
So the reason that the Federation 'owns' this and every planet in its area of influence is not because of its high morals but because it has a lot of big guns. And although I hate to side with Picard (in just this one case) - the only thing that differentiates the Federation from the Klingon Empire in this case would be that the Klingons would kill or enslave the Baku where the Federation will just move them but to where? Some less liked planet. Somewhere out of the Federation?