The most likely answer is that they didn't think about it or didn't understand or didn't care. But on the off chance they did, perhaps they thought the DNS provider would enforce the ruling worldwide.

Same reason copyright abusers threaten people that help remove the DRM from their Amazon-bought e-book so it can be read on their non-Amazon bought e-reader with a $250,000 fine and five years in prison for circumventing a digital lock using DMCA, because it's what the legal API allows them to achieve their end goal.

It's not about if it makes sense from a moral point of view.

You would if you could and it'd probably work.

I believe the position of the French government is that anyone in the path of a crime can be ordered to block the part of the crime that relates to them, without having any liability for the crime. So quad9 are not criminals for not blocking pirate sites, but still have to block specific sites when ordered.

Because they can.

Attacking the people doing the actual bad things is hard, attacking a single unified organization is easy.