The situation had evolved very fast. Even on Saturday morning, it was announced that ATB would be going ahead the next day but with additional COVID tests for arrivals at SIN at a cost of S$196, where passengers would get it done at Changi, and take private transport directly to accommodation and self quarantine before the results are released. (Which is a friendlier approach than arrivals at HKG, where passengers have to wait at HKIA, and leave only after the results are released.)
Then the announcement came on Saturday evening that it would be deferred for a fortnight.
Meanwhile SQ is giving full refund to passengers who now opt not to travel due to the deferment of ATB. But have not heard if CX is doing the same.