Is it MAY be non-neutral or MUST be non-neutral, you ask. The answer is wide open. But in any serious contract you wouldn’t leave that open.

You could make a legal argument that people who can block infringement are obligated to take action.

Or you could examine whether it’s possible, as an engineering question, to have a neutral network that also enforces copyright. To find out the answer to that, you have to define what it means to enforce copyright in the core. That’s why my posts here started with the question of how copyright enforcement would be implemented.