Yes, 2x is clearly "disproportionate", but it's a far cry from being obviously significant. If you assume that pollution is not significant in best neighborhoods, then it's not greatly significant in worst, because twice something insignificant is still hardly significant. Replace oil wells with something else that's clearly harmful: murders. Imagine the worst neighborhoods had twice as many murders as the best ones. This would actually be improvement over the status quo: worst neighborhoods are far more dangerous than just 2x!
> Even the last paragraph highlights the fact the pollution is a high factory in these districts.
It does no such thing. It says that wells can contribute to ongoing pollution. That does not mean that it does, and it does not even quantify the contribution of wells to pollution, nor does it even show that the worst districts are significantly more polluted in the first place.
The point of this study is to corroborate the narrative of redlined district being significantly more polluted than the "best" districts, and that this is why residents of these districts and their descendants have worse outcomes today. It shows something that's not very interesting on its own (just twice the number of oil wells). However, it's clearly successful in building narrative, given that it convinced you that it provides evidence for it.