In 25 words . . .

[bossman72]

It's really not deceiving to the baserunner. All base runners are taught to watch the pivot foot of a RHP at first base. When the pivot foot moves, they go back.

I mean, if they allow a jump turn (where the pivot foot also moves toward third base), why would the jab step not be legal as well?

This move has been legal for a very long time. Don't try to be a crusader against it since it's not EXACTLY by the book. I guarantee if you don't balk this you will not hear a peep from either dugout all game. If you do balk it... well... good luck