Having done the search you recommended, it sounds like the story is best told in the other direction: CyangenMod signed an exclusive deal with one of OnePlus's competitors for the Indian market, totally screwing them over in India, making them forced to release their device there without CyanogenMod. If they are also now dropping support for Cyanogen everywhere due to this (which isn't clear), I honestly could not blame them: a better telling of the story is "sadly it looks like CyanogenMod is moving away from OnePlus".