it says "Regardless of your advice to Halros while gathering the Rangers during Vol. III, Book 1, he eventually joins the Grey Company on their road south and takes part in a quest instance at Mirobel in Eregion."
so I guess his conscious/duty etc get the better of him and he goes with the Gray Company.
Gratz for the necromancy
Unless they changed something with those quests Halros will stay in the Shire if you tell him to. I have two characters one of whom told him to stay and other one to go. If you do the instance in Mirobel with a character that didn't tell Halros to go south he will not be there, instead of him you'll meet another one (I think it was Radanir).
Re-ni-AN-nen - strayed (ppt. of renia- 'to stray')
Aeled Reniannen, Defender of Middle-earth ~ Nendhiniel, Forge-Warden : Captain and Wardenette from [EN-RP] Laurelin
Fluffrash, Blade of Barashish ~ Nathraen, Conqueror of Towers : Warg Puppy and Spider Tailor from the darker side thereof
Faradwen, Swift-Arrow : Huntress from [EN-RE] Landroval
As if in answer there came from far away another note. Horns, horns, horns. In dark Mindolluin's sides they dimly echoed. Great horns of the North wildly blowing. Rohan had come at last.
~~~~~
Kári was a little Dwarf. / Smaller than you or me. / And wherever Kári went / He took his axe… or three.