Jabba the Hutt operated outside the realm of the law, be it the crushing restrictions of the Empire or the more open rule employed by the Rebellion. He was a gangster, after all. He did his own thing, surrounding himself with his own type in order to rule his criminal empire. So, in Jabba's Realm, the new expansion coming for Imperial Assault, there's plenty of Mercenary models. That's not to say there aren't Imperials as well, mind you.
Used throughout his palace, Gamorrean Guards are an ever-present symbol of the Hutt's rule. While pretty much everyone in the place is an outlaw, that doesn't mean you can just do whatever you want, lest the guards come after you. There's also the Weequay Pirates, whose skills seem to make luck take a second look. As for Imperials, you've got Stormtroopers with jet packs in this set. Now, Stormtroopers aren't generally known for their long military careers. You'd think strapping rockets to their backs would only make that a shorter trip. But there we are, then.