I didnt say he was a cop but he is a well-respected citizen. And no I tend to think you're wrong if you were to put a staple on a Desert stalker who "Works for the Queen" Which by his own talk (not many of them do) in old game i would in fact call him FBI. He's above a gaurd though not above much else. He enjoys the privileges that affords him and as far as original game goes he LOVEs his kingdom and wants what's best for it. It was also a scene that said yes you can have slaves but with that comes responsibility now thats out the window. I'll talk more on it when i replay the whole game. Maybe he added more but it seems like they are making him generally not even care about his own culture which seems weird. He was always a loner but never an outsider.
Your main character may love his kingdom but mine doesn't. It's in your head. He likes Zeta but he is also very critical with it and he doesn't share half of their beliefs. He doesn't share their religion, he doesn't share their prejudices, he is above their politics. He may bend the knee to their queen but he makes very clear that's to keep appearances. He recognizes the power of her army but he has many situations where he can make clear to the queen that he is not to be toyed, he talks with her as an equal. Not her servant or employee. That's why she likes him.
Desert stalkers are clearly inspired in Spectres from the mass effect trilogy. They are free agents that, on paper, may help the zetan city but in practice, they have freedom to do what they want. They use technology that no other citizen is allowed and they live beyond the limits of the city. We are told repeatedly, that most desert stalkers don't give a damn about the queen and are not to be trusted.
When Zosar (the mc master) is found leading an opposing faction, nobody wonders why he betrayed Zeta, because he didn't. In the worst case scenario, he may have betrayed his own beliefs, but we know that's bullshit. Beliefs change over time, you don't betray them, you outgrow them.
The main character here is working for many countries/oposing factions: The raiders from Adira, the mutants, the decayed. He is not doing it as a Zeta representative, he does it because he is a free agent and everybody knows it. He is a link to Zeta, not an fbi agent and for sure, not a cop. His work is not to keep zetan law. He can make that his work, if he wants to. But I don't think the main character here is like that. He is way beyond those limitations. He knows those laws and follows them when likes to. And that's it.