The bug
Despite MC-175030 being fixed, golden helmets aren't fixed. Piglins are still capable of removing the curse of binding carved pumpkin after they have fully inspected a golden helmet.
To reproduce
Spawn a piglin
Throw an enchanted carved pumpkin with curse of binding near the piglin
Just wait for the piglin to pick up the pumpkin
→ ✔ The piglin is wearing the carved pumpkinThrow a golden helmet near it
→ ❌ The piglin inspects the helmet, and then proceeds to remove the pumpkin on its head, thus lifting the curse.
This affects more than just carved pumpkins. A piglin is able to remove any curse of binding item if the piglin is trying to replace it with a gold item. (The version I tested in was 1.16 pre-release 2.)