Why would "Ground Stop" be ordered but limited to West Coast airports if an EMP was truly expected?
A half-azz Yung Fat mid-height EMP over the Sea of Japan or even the other side of Japan would maybe be a regional theater operation with the locus Japan + 2500mi radius, so it would encompass South Korea, Philipines, and Taiwan.
Not one of them called for "Ground Stop".
This smells like a pre-programmed scenario to reveal to the CCP how Xiden'a West Coast civilan ATC would react to a 'rogue' EMP release by the North Koreans PLA.
"Hunter Biden, please pick up the white courtesy phone to collect your check."
Maybe.
Although I make fun of them routinely, N. Korea has pitched some satellites into fairly complicated orbits before.