I believe Poe is talking about the lowly status of being a scavenger in that case, not suggesting that it is a bad thing. Stormtroopers are grunts, and being a spice runner suggests that the person is in a pretty destitute situation.
I agree that there really isn’t anything you can replace it with, although if I think of something I’ll let you know!
Being a spice runner isn’t exactly grunt work, though; I get where you’re coming from, but I personally find it hard to read the scene that way, considering Poe seems embarrassed about having a shady past contrasted to his squeaky clean Resistance Leader image.
I could always cut his line to Rey, but I really like how smoothly it rolls into Zorii’s retort and keeps the scene moving. I’ll just leave it in square brackets for now and come back to it if either of us think of anything.
(I should explain - anything I write which I know is just placeholder text, I put in square brackets, so it’s easy to search the document later and find it. My own novels’ early drafts have a lot of “[one-liner]”, or “[smth adj]” when I can’t think of the right adjective.)