Steins;Gate seems to operate on a logic wherein Okabe building a phone wave tomorrow wouldn't result in time being changed until tomorrow actually happens, but someone like Suzuha can arrive from the future in any timeline where World War 3 happens before the time machine is actually built. Even so his confusion is understandable to me, it's incredibly worrying that he can't pin down a cause for his reading steiner activating.

I think Daru was just spitballing ideas, I think it's good that every possibility is being accounted for.

The adaptation is good whenever it is following the VN. However, for various reasons, some aspects of the VN are going to have to be changed either for time or coherency. As I argued in the post, the first of these changes isn't one I thought was handled too well... But I'm glad it's working for someone who hasn't read it like yourself.