Alak: very good point. Serious kudos, o ye defender of the canon...
Here's what I found regarding Celeborn's departure:
Appendix B: "After the passing of Galadriel in a few years Celeborn grew weary of his realm and went to Imladris to dwell with the sons of Elrond. In the Greenwood the silvan elves remained untroubled, but in Lorien there lingered sadlyonly a few of its former people, and there was no longer light or song in Caras Galadhon."
So if you think it makes more sense, your character could be "lingering" instead of "guarding."
Good work.