FWIW, I think I would have the same bedtime during the week as on the weekend, just for consistency's sake. That way he would always have the same amount of time to read. A routine. A routine can lead to less arguing and debate because you can just say, "Sorry, that's how we always do it. Those are the rules." Then, if you find that he would like still more reading time, offer to let him go to bed earlier, knowing that the "lights out" time never changes.

I can't see punishing a child for doing something that is as great for them as reading, but I definitely see the need to set limits.

She thought she could, so she did.