I have been wondering that too honestly. As, iirc, the update notes originally said the plan was for them to make it so they could be summoned within the Adoulin areas, but alas they cannot. Where as I love the Trust NPCs and have they have done for the game; the fellows have been around much much longer and deserve the same kind of love. I have had mine since I could do the quest on my first job I took to 75 many years ago and he has lvled along side me. Where as I don't mind lvling him to 99 for something fun to do, I would at least like to do it in an area where I could earn compasity points from every mob.