Even with a user agreement I think they need to gate their service behind that agreement, otherwise the agreement is optional and open ports are open for use.

Even with a user agreement I think they need to gate their service behind that agreement, otherwise the agreement is optional and open ports are open for use. You still need to form a valid contract - no notice, no assent, no contract. If there's a gate that's being bypassed then this all changes but it doesn't seem like there is - and it doesn't seem like they can add one without breaking existing printers.