I think Mercantile is a fation that is supposed to take advantage of other faction's weaknesses. They have access to pretty much everyone, and everyone else will be fighting a different faction. Merchants would be leaping on a scenario that's advantageous to them at any turn.
So, in effect, I think they wanted the Mercs to have the chance to attack every faction as those factions are fighting amongst the others. Bottom feeders and opportunists.
Not going to play off like that at all, buuuut.