After the game, the NFL explained why the play was ruled that way.
“Had the clock been running at the snap, then by rule an illegal shift would convert to a false start,” a league spokesman said, via The Athletic. “Since the clock was stopped (spike on the second-down play), an illegal shift is a live ball foul.”
Surely, that explanation will satisfy all the conspiracy theorists who are convinced that the league just gifts calls (and wins) to the Chiefs, so there’s nothing more to worry about on that front.