I agree that the order is clear and plain on its face and you can see him. Emancipation has nothing to do with this.
Regarding whether you see him or not, that's up to you. I know they will take it out on him because this is what parents like these do.
If they don't know you're seeing him, and you have an order that says you can, why not see him away from the parents? If they won't know about it, at least you will have your grandson and you can see him when you both make arrangements for it.
There is NOTHING criminal about this, and there is NOTHING that calls for emancipation, so that's incorrect. I agree that the order is plain on its face. It is the parents who are interpreting it that way and they are wrong.
I would not respond to the letter either. It's going to inflame the situation.
My suggestion is to see him outside of the parents' area, and what they don't know won't hurt them. You have a legal right to see your grandson because the order says you do.
This should answer your question now. I was thrown off because you talked about amending but it is not something that needs amending. The order is clear and plain on its face.