It is not a "legal" formation...
Dropping a player back to simulate a possible kick on every down, is an obvious attempt to skirt the rules. If this offense is so clean and above board, why do the wait until the last second to show who is eligible? Deception is fine, up to a point. Other rules have been put in place to stop loophole violations. No fake footballs on jerseys, first the Minnesota shift, then The Norte Dame shift were outlawed to keep from having entire backfields in motion at the snap. People who come up with these types of offenses, know they will be ruled, "legal" or "illegal" when they become popular. It's how the game stays relevant. At one time the forward pass was, first illegal, then slowed by heavy costs, (i.e. an incomplete pass was considered a fumble and could be advanced by the defense only, if the offense recovered, it was placed at the spot of the attempt and it would be the next down.) as it became more popular the rules came around to what they are today. This A-11 will either stand the test of time, or disappear like the Wishbone, relegated to the annals of history.