Firstly, Celeborn is also Teleri. Practically all the Elves in Beleriand were members of the Teleri, otherwise they were Noldor. The Teleri divided into Nandor (the Silvan), the Laiquendi, and GreyElves of Mithrim, the Doriath Elves.

Celeborn is a relative of Thingol ,who was his granduncle, who was accounted by all the Elves in Beleriand as their King, until the Noldor came. Galadriel's grandfather is Olwe, who was Thingol's brother.

So they are the 'senior' Elves there, by Telerin ancestry alone.

Furthermore, the Silvan Elves welcomed the higher Sindarin and Noldorin Elves and enriched their culture by doing so. The Sindarin Princes (eg Celeborn) were taken by the Silvan as Kings, like Thranduil Legolas' father.

In one version, Amroth the King of Lorien was Celeborn's son- so when he drowned, his father and mother took his place as rulers, though not king. In another version, Celeborn himself is a Telerin Elf of Valinor- that's high enough for you?

Also it was a good political decision. Galadriel was friendly with Khazad-dum, Elrond and Hollin on the other side, while Celeborn was friends with Oropher and Thranduil on the east Anduin. Also, it would keep the local Men from intruding into the forest, knowing that a big 'sorceress' in Galadriel lived there.

Another reason is that a King of the Galadhirrim made a pact with the Ents-judging by Celeborn's banter with Fangorn in the book, it must have been someone he knew in Lorien.

There is but one task remaining in Arda-we,the Dragons of Valinor will make it happen.

Lone resident of the Republic of Gondor

PO-TA-TOE-S not PO -TAH-TOE-S!