Rogues do business with everyone that is profitable. Artifacts from Sairs, Cardamine from Outcasts, Red Diamonds from Hessians. Everything brings cash, why they should care where it comes from?
As far as I am aware, artifacts get into Liberty mostly through Hogosha dealings rather than direct Corsair ones. It goes like this:
- Corsairs trade with Hogosha on Lux Liner Hawaii
- Hogosha then sell to buyers on New Tokyo but also deal with the Lane Hackers on Leiden Base
- Lane Hackers front some of it to the Rogues, who then act as middlemen
That's more or less how it looked in the vanilla campaign, if we're bringing that up as a reference. It shows another very interesting thing as well, mainly how the 3 main smuggling commodities each take different routes and different factions to smuggle into Liberty, i.e.
- Cardamine takes Junker/Hacker smugglers all the way from Cali Base, through Bretonia to Magellan for Hackers, and Alcatraz in California for trading with the Rogues (a good population of which is confirmed to be addicted to Cardamine) who then act as pretty much vendors for individual buyers <- Cardamine comes in from the west
- Artifact trade comes in from Kusari through Galileo as explained above <- Artifacts come in from the north
- Diamond smuggling routes go through Hamburg, Bering and Hudson (the Xenos want to get a cut, while the Hessians let the Junkers smuggle the stuff, the Unioners provide security for a cut, and it's sold to the Rogues who again act as middlemen) <- Diamonds come in from the south
Another thing to mention is that as far as I am aware, vanilla has never intended Rogues to be an organisation with an actual command structure, more like a label for relatively loose groups of pirates in Liberty who can pursue different goals and different diplomacies. This means that some groups can trade exclusively with the Outcasts, be completely cardamine addicted etc. while others can probably fancy themselves more like art dealers and import diamonds and artifacts <- because these two trades happen away from each other, it is very unlikely that even though the groups supplying the two are mortal enemies, that their transports will even meet each other and that any diplomatic fallout will occur for any Rogues in the first place.
In the end it's all down to turf intrusions in the particular case of smuggling I would say.