I'd argue that Zoners don't really have anything to back up Iridium mining (I've probably triggered several dozen people) but I think there's wider implications beyond that.
Omicrons are completely lacking any sort of real piracy activity. When the notion of Iridium mining implementation was announced I was hopeful that we'd finally start to see some piracy in the region, which in turn would greatly help finally create the ambient activity the region needs. However from a activity/diplomatic POV it worries me greatly that a neutral ID which pretty much every unlawful ID relies on to use their bases for pirate activity has access to the highest mining bonus on Iridium. Combine that with the recent change whereby CoF laws can be enforced system-wide, we're pretty much just going to see unlawful players locked out of any Omicron piracy dare they risk an FR5 that will just utterly neuter their unlawful activities elsewhere. And whilst there are 3 other IDs with the same bonus, arguably the Zoner ID is already extremely attractive for trading and there's no doubt it's going to be a more attractive ID for mining too.
Instead I'd much prefer if Corsairs got a mining bonus on Iridium. Many people are discontent that the Corsairs have been forcefully 'booted out' of Omicron Delta and the southern Omicrons in general. If Corsairs got a mining bonus on Iridium and say the Iridium field was in Omicron Delta rather than lost, Delta would basically become an Edge Worlds version of Tau-23 and be a great melting pot of activity of IDs from all parts of the alignment spectrum. It'd definitely encourage Corsairs to come back into that region in all forms, and furthermore it also still puts the AI IDs in good proximity to the field, rather than (seemingly) making it exclusive for Core, Order and Zoner IDs. The level of ambient activity would be amazing. I actually made a concept map a while back of a more (imo) activity-catering Omicron Delta. Although Azurite is kinda doing this minus Corsairs and AI which is kinda the same I guess, but I'd feel Iridium might fit that bill better RP and activity wise.
Inb4 "haha ur only saying this cus u hate Zoners!!11"
If not for people flippantly dishing out FR5s and Zoner players forcefully enforcing their neutrality on people then a Zoner mining bonus would be completely harmless. However unfortunately that is not the case. All in all I don't feel like a Zoner bonus on Iridium is going to be healthy for activity in the long run. Quasi-lawful FR5s are extremely problematic for activity when it comes to unlawful factions. Leave it to the actual factions that are based in the Omicrons, because those IDs are the ones that need a boon to their player bases (especially in the case of factions like AI/PRIME).
As a slightly zany suggestion, maybe give Nomads a mining bonus on some new commodity? It could be like what old normal scrap used to be for Junkers, but with better balancing I'd hope. If it was placed in somewhere like Iota, it'd create ambient activity in the Nomad home system and provide incentive for factions like Core and Order to raid (Iota has always been incredibly empty). And Nomads are a race of aliens, not just outright monsters. Creating some sort of, dare I say, 'civilian' life of them could be a possibility, right? A bit of resource gathering for their cause?