Yeah, or more precisely, with raise_built set to false here.
I'm creating the hidden generators in the pole "silently" so that other mods don't interfere with it.
My thought when I wrote it was that this is a hidden entity that the player shouldn't know about, and thus other mods don't need to know about it either, because there's a possibility of unwanted interactions. For example, let's say a mod wants to prevent placing generators on a specific tile by listening on the creation event. That would backfire here, because the poles would then be unplacable on that tile too. However, this might be too restrictive for mods actually improving the experience, like yours. Maybe I can raise it in the rewrite, not sure yet.
Theoretically I could just change it to true now, but it might have either side-effects, and I don't want to spend too much time until I rewrite all the logic in Factorio 2.0. This was the first real mod I wrote, so the code is really spaghetti and unmaintainable, especially the placement logic.