i believe that senders can't control the packages once they're shipped, so i doubt he's trying to buy extra time. your tracking says "Arrived at USPS Regional Facility", so that's who's in control now. and i've usually had poor tracking from USPS. btw, mine shows no motion for three days, but still says it's due to be delivered today.
i've frequently had it happen where USPS tracking shows no changes, the item shows up at my door, and then suddenly USPS shows tracking for every step of the way, although it wasn't showing earlier the same day.
ISC NEW YORK NY(USPS), Processed Through Facility -> Your item has been processed through our facility in ISC NEW YORK NY(USPS) at 10:52 am on March 7, 2020.
2020-03-02 22:41
Origin Post is Preparing Shipment
2020-03-02 22:41
CHINA, GUANGZHOU EMS, Processed Through Facility
2020-03-02 22:40
CHINA, GUANGZHOU EMS, Processed Through Facility
2020-03-02 21:14
CHINA, GUANGZHOU, Processed Through Facility
2020-03-02 15:31
CHINA, Acceptance