Isn't the fact that nobody involved in this seizure could tell that they weren't AirPods counterfeits a form of evidence that OnePlus Buds may in some circumstance be AirPods counterfeits?
If you want your customers to be assured of getting the genuine article you should put an actual trademark on your product. Apple shouldn't get to claim that anything with a minimalist design is a counterfeit Apple product.
Apple never gets enough credit for their design work in the general tech community. Lots of design work can look “obvious” or minimalist in hindsight.
But ianal