I'm afraid that this is most likely due to a certain paranoia in roleplay about the whole issue. The conflict caused Daumann to lose trust in OSI, I mean before they had good relations actually, but that was just replaced with caution back then.
Also, nothing prevents you from bountying your tormentors sirius-wide, it's a logical consequence from their actions.
Comparing this to England and German situation is not entirely accurate, I think. Contrary to England and Germany, there has been zero reconciliation between Daumann and OSI or even between Rheinland government and OSI. Although the OSI has attempted to solve this, I can understand why Rheinland government would still be grumpy about the subject.
It also honestly isn't as easy as out of sight, out of mind. While they can not confirm directly that OSI is still shoving supplies to hessians, they also have no evidence that denies it. Given that the trust is lost, they are still quite wary.
