This is just a part of US strategy of news making.
First, US vows to react if China builds a new island. Was there any evidence that China would be doing that? No. US simply creates a sensational news out of thin air.
Then, US spreads the news on ADIZ in SCS. Was there any evidence that China would be doing that? No. US simply creates another sensational news out of thin air.
They will spread such news as many times as they can to give people an impression that China is currently doing that. They provide "materials" for all anti-China news outlet to have something to run on, such as this one that clearly states those islands belong to either Vietnam or Philippine, but definitely not China.
No doubt US is a master of psychological manipulation.