Service parts and restricted availability

Does anyone know where I could source a drive shaft seal for my Gen1 quad rear drive unit? While my truck is still under warranty, it is in an unsupported location, and shipping it to a service center would cost me around $5k. The issue is well identified, and the part is only $40. Unfortunately, Rivian won't sell me the part because I am not a fully certified service center. It doesn't seem to make sense why even a seal is restricted, when other components (even major ones) can be freely ordered.