I imagine that who his grandmother was has a lot to do with why they would want him to come along. I would think that the story of his great grandparents would be one of those tales told to rally people against the fatanen...and in the eyes of edhil, fatanen protesting their own kind is a major win. I also know that this "representative of the high king" (who I imagine being a very freaky looking woman, perhaps not all fatanen blood? I almost imagine her being part Edhil...hmm...) would have helped plant him, so she must be a sort of double agent herself. Reverse to what I said before, and Edhel that is rallying for the High King would be very unusual, therefore she gets away with it easier. 

I just brainstormed all over this OOC...To sum it up, A half-edhil sleeper agent helps plant him among the group. Though she was hoping it was Hue's father who took the quest, she accepts Hue's offering to go in his father's stead. She does this because he, unlike her, is expendable.