Nael van Darnus is part of the Garlean strong force but his agenda is separate from the Garleans. He's been using them to further his own agenda.

The empire has other goals...and as we have seen in previous concept and mention there will be more Garlean stronghold areas as well as their territory opening up east of Ala'Mhigo...which we hopefully will also see in the future as it's a city state occupied by the Garleans...which the citizens of Lil Ala'Mhigo are building a resistance to reclaim their land.