I don't take the official statement at face value. When the Beijing facilities were taken off-line in 2006 for the runup to the 2008 Olympics (and the main skating facility there needed a complete structural rework, not just minor changes that are needed now), China's GP's were held in Nanjing and Harbin. Since then, Shanghai has also hosted. There are also other cities that could host. So using lack of available physical facilities in China isn't a plausible excuse. This has got to be something political, either China vs the ISU or something internal inside China with the Skating Federation. I'm normally not big on conspiracy theories but it is possible that
@forthewin is correct on the underlying reasons. And the timing of conveying the decision to the ISU would support a retaliation for something that happened earlier in 2018.