Klingon ownership of the briar patch before the baku arrived gives Klingons/the federation prior claim to the briar patch. The baku are nothing more than tresspassers. You actually think tresspassers have any claim to the land they tresspass on? If yes, the federation doesn't share your opinion. If it would, the romulans would have long ago conquered the federation by settling a few hundred romulans on every non-inhabited federation planet and claiming it as their own. Except the briar patch is NOT the baku's world - homeworld or otherwise. Tresspassing on a land does NOT make it yours. And NOT harvesting the immortality particles does a HUGE disservice to the member worlds of the federation and the billions of beings inhabiting them. Legally, the baku have no legitimate claim on the immortality planet. Morally, letting billions suffer for the vanity of 600 is obscene.