This is completely irrelevant to me. I do not care if I can kill children or not. I would not do so even if I had the option. I did do it in Skyrim with the appropriate mod from time to time, because that game is a sandbox and I found it amusing to send people (no matter their age) flying across the city with fus-ro-dah, but in a more story-driven game where player agency is much less important to the core experience (for better or worse), I understand and respect their decision.
With that said, I also respect the opinion of those who feel you should be able to kill everything that moves. It bothers me that so many people are metaphorically crucifying people for wanting the same rules to apply to all NPCs. The assumption should not instantly be that these players get some sort of sadistic enjoyment out of murdering kids (in a game) in particular. Perhaps they just get sadistic enjoyment out of killing anything in a virtual environment.
I like shooting wolves in RDR2. Doesn't mean I want to shoot wolves in real life. Heck, I have a hard time killing cockroaches, and rats? Forget about it. I've got two of the little bastards as pets (the pet breed, not wild rats forced to live in captivity), and they are the sweetest creatures I've ever had the pleasure of interacting with.
Again, I see nothing wrong with CDPR's decision. It's smart for business. We had a similar discussion about Age-Only ratings in the Sex Thread, which I think was closed quite some time ago. At the end of the day, CDPR is no longer a teeny weeny indie dev. To survive at their size, they must appease ratings boards and distributors to some degree. Let's just be glad they've retained most of their integrity.